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Decibel

The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a power ratio of 101/10 (approximately $1.26$) or root-power ratio of 101/20 (approximately $1.12$).

The unit expresses a relative change or an absolute value. In the latter case, the numeric value expresses the ratio of a value to a fixed reference value; when used in this way, the unit symbol is often suffixed with letter codes that indicate the reference value. For example, for the reference value of 1 volt, a common suffix is "V" (e.g., "20 dBV").

Two principal types of scaling of the decibel are in common use. When expressing a power ratio, it is defined as ten times the logarithm with base 10. That is, a change in power by a factor of 10 corresponds to a 10 dB change in level. When expressing root-power quantities, a change in amplitude by a factor of 10 corresponds to a 20 dB change in level. The decibel scales differ by a factor of two, so that the related power and root-power levels change by the same value in linear systems, where power is proportional to the square of amplitude.

The definition of the decibel originated in the measurement of transmission loss and power in telephony of the early 20th century in the Bell System in the United States. The bel was named in honor of Alexander Graham Bell, but the bel is seldom used. Instead, the decibel is used for a wide variety of measurements in science and engineering, most prominently for sound power in acoustics, in electronics and control theory. In electronics, the gains of amplifiers, attenuation of signals, and signal-to-noise ratios are often expressed in decibels.

History
The decibel originates from methods used to quantify signal loss in telegraph and telephone circuits. Until the mid-1920s, the unit for loss was miles of standard cable (MSC). 1 MSC corresponded to the loss of power over one mile (approximately 1.6 km) of standard telephone cable at a frequency of $5,000$ radians per second (795.8 Hz), and matched closely the smallest attenuation detectable to a listener. A standard telephone cable was "a cable having uniformly distributed resistance of 88 ohms per loop-mile and uniformly distributed shunt capacitance of 0.054 microfarads per mile" (approximately corresponding to 19 gauge wire).

In 1924, Bell Telephone Laboratories received a favorable response to a new unit definition among members of the International Advisory Committee on Long Distance Telephony in Europe and replaced the MSC with the Transmission Unit (TU). 1 TU was defined such that the number of TUs was ten times the base-10 logarithm of the ratio of measured power to a reference power. The definition was conveniently chosen such that 1 TU approximated 1 MSC; specifically, 1 MSC was 1.056 TU. In 1928, the Bell system renamed the TU into the decibel, being one tenth of a newly defined unit for the base-10 logarithm of the power ratio. It was named the bel, in honor of the telecommunications pioneer Alexander Graham Bell. The bel is seldom used, as the decibel was the proposed working unit.

The naming and early definition of the decibel is described in the NBS Standard's Yearbook of 1931:

In 1954, J. W. Horton argued that the use of the decibel as a unit for quantities other than transmission loss led to confusion, and suggested the name logit for "standard magnitudes which combine by multiplication", to contrast with the name unit for "standard magnitudes which combine by addition".

In April 2003, the International Committee for Weights and Measures (CIPM) considered a recommendation for the inclusion of the decibel in the International System of Units (SI), but decided against the proposal. However, the decibel is recognized by other international bodies such as the International Electrotechnical Commission (IEC) and International Organization for Standardization (ISO). The IEC permits the use of the decibel with root-power quantities as well as power and this recommendation is followed by many national standards bodies, such as NIST, which justifies the use of the decibel for voltage ratios. In spite of their widespread use, suffixes (such as in dBA or dBV) are not recognized by the IEC or ISO.

Definition
ISO 80000-3 describes definitions for quantities and units of space and time.

The IEC Standard 60027-3:2002 defines the following quantities. The decibel (dB) is one-tenth of a bel: 1 dB = 0.1 B. The bel (B) is 1⁄2 ln(10) nepers: 1 B = 1⁄2 ln(10) Np. The neper is the change in the level of a root-power quantity when the root-power quantity changes by a factor of e, that is 1 Np = ln(e) = 1, thereby relating all of the units as nondimensional natural log of root-power-quantity ratios, $1⁄2$ = $1⁄2$ = $1⁄4$. Finally, the level of a quantity is the logarithm of the ratio of the value of that quantity to a reference value of the same kind of quantity.

Therefore, the bel represents the logarithm of a ratio between two power quantities of 10:1, or the logarithm of a ratio between two root-power quantities of $1⁄2$:1.

Two signals whose levels differ by one decibel have a power ratio of 101/10, which is approximately $1 dB$, and an amplitude (root-power quantity) ratio of 101/20 ($0.115 Np$).

The bel is rarely used either without a prefix or with SI unit prefixes other than deci; it is preferred, for example, to use hundredths of a decibel rather than millibels. Thus, five one-thousandths of a bel would normally be written 0.05 dB, and not 5 mB.

The method of expressing a ratio as a level in decibels depends on whether the measured property is a power quantity or a root-power quantity; see Power, root-power, and field quantities for details.

Power quantities
When referring to measurements of power quantities, a ratio can be expressed as a level in decibels by evaluating ten times the base-10 logarithm of the ratio of the measured quantity to reference value. Thus, the ratio of P (measured power) to P0 (reference power) is represented by LP, that ratio expressed in decibels, which is calculated using the formula:

L_P = \frac{1}{2} \ln\!\left(\frac{P}{P_0}\right)\,\text{Np} = 10 \log_{10}\!\left(\frac{P}{P_0}\right)\,\text{dB}. $$

The base-10 logarithm of the ratio of the two power quantities is the number of bels. The number of decibels is ten times the number of bels (equivalently, a decibel is one-tenth of a bel). P and P0 must measure the same type of quantity, and have the same units before calculating the ratio. If P = P0 in the above equation, then LP = 0. If P is greater than P0 then LP is positive; if P is less than P0 then LP is negative.

Rearranging the above equation gives the following formula for P in terms of P0 and LP:

P = 10^\frac{L_P}{10\,\text{dB}} P_0. $$

Root-power (field) quantities
When referring to measurements of root-power quantities, it is usual to consider the ratio of the squares of F (measured) and F0 (reference). This is because the definitions were originally formulated to give the same value for relative ratios for both power and root-power quantities. Thus, the following definition is used:

L_F = \ln\!\left(\frac{F}{F_0}\right)\,\text{Np} = 10 \log_{10}\!\left(\frac{F^2}{F_0^2}\right)\,\text{dB} = 20 \log_{10} \left(\frac{F}{F_0}\right)\,\text{dB}. $$

The formula may be rearranged to give

F = 10^\frac{L_F}{20\,\text{dB}} F_0. $$

Similarly, in electrical circuits, dissipated power is typically proportional to the square of voltage or current when the impedance is constant. Taking voltage as an example, this leads to the equation for power gain level LG:

L_G = 20 \log_{10}\!\left (\frac{V_\text{out}}{V_\text{in}}\right)\,\text{dB}, $$ where Vout is the root-mean-square (rms) output voltage, Vin is the rms input voltage. A similar formula holds for current.

The term root-power quantity is introduced by ISO Standard 80000-1:2009 as a substitute of field quantity. The term field quantity is deprecated by that standard and root-power is used throughout this article.

Relationship between power and root-power levels
Although power and root-power quantities are different quantities, their respective levels are historically measured in the same units, typically decibels. A factor of 2 is introduced to make changes in the respective levels match under restricted conditions such as when the medium is linear and the same waveform is under consideration with changes in amplitude, or the medium impedance is linear and independent of both frequency and time. This relies on the relationship
 * $$ \frac{P(t)}{P_0} = \left(\frac{F(t)}{F_0}\right)^2 $$

holding. In a nonlinear system, this relationship does not hold by the definition of linearity. However, even in a linear system in which the power quantity is the product of two linearly related quantities (e.g. voltage and current), if the impedance is frequency- or time-dependent, this relationship does not hold in general, for example if the energy spectrum of the waveform changes.

For differences in level, the required relationship is relaxed from that above to one of proportionality (i.e., the reference quantities P$0.115$ and F$\sqrt{10}$ need not be related), or equivalently,
 * $$ \frac{P_2}{P_1} = \left(\frac{F_2}{F_1}\right)^2 $$

must hold to allow the power level difference to be equal to the root-power level difference from power P$1.259$ and F$1.122$ to P$0$ and F$0$. An example might be an amplifier with unity voltage gain independent of load and frequency driving a load with a frequency-dependent impedance: the relative voltage gain of the amplifier is always 0 dB, but the power gain depends on the changing spectral composition of the waveform being amplified. Frequency-dependent impedances may be analyzed by considering the quantities power spectral density and the associated root-power quantities via the Fourier transform, which allows elimination of the frequency dependence in the analysis by analyzing the system at each frequency independently.

Conversions
Since logarithm differences measured in these units often represent power ratios and root-power ratios, values for both are shown below. The bel is traditionally used as a unit of logarithmic power ratio, while the neper is used for logarithmic root-power (amplitude) ratio.

Examples
The unit dBW is often used to denote a ratio for which the reference is 1 W, and similarly dBm for a 1 mW reference point. L_G = 10 \log_{10} \left(\frac{1\,000\,\text{W}}{1\,\text{W}}\right)\,\text{dB} = 30\,\text{dB}. $$ L_G = 20 \log_{10} \left(\frac{31.62\,\text{V}}{1\,\text{V}}\right)\,\text{dB} = 30\,\text{dB}. $$ (31.62 V / 1 V)2 ≈ 1 kW / 1 W, illustrating the consequence from the definitions above that LG has the same value, 30 dB, regardless of whether it is obtained from powers or from amplitudes, provided that in the specific system being considered power ratios are equal to amplitude ratios squared. L_G = 10 \log_{10} \left(\frac{10\text{ W}}{0.001\text{ W}}\right) \text{ dB} = 40 \text{ dB}. $$ G = 10^\frac{3}{10} \times 1 = 1.995\,26\ldots \approx 2. $$
 * Calculating the ratio in decibels of 1 kW (one kilowatt, or $1$ watts) to 1 W yields: $$
 * The ratio in decibels of $1$ V ≈ 31.62 V to 1 V is $$
 * The ratio in decibels of 10 W to 1 mW (one milliwatt) is obtained with the formula $$
 * The power ratio corresponding to a 3 dB change in level is given by $$

A change in power ratio by a factor of 10 corresponds to a change in level of 10 dB. A change in power ratio by a factor of 2 or $2$ is approximately a change of 3 dB. More precisely, the change is ±$2$ dB, but this is almost universally rounded to 3 dB in technical writing. This implies an increase in voltage by a factor of √2 ≈ $0.115$. Likewise, a doubling or halving of the voltage, corresponding to a quadrupling or quartering of the power, is commonly described as 6 dB rather than ±$1.259$ dB.

Should it be necessary to make the distinction, the number of decibels is written with additional significant figures. 3.000 dB corresponds to a power ratio of 103/10, or $1.122$, about 0.24% different from exactly 2, and a voltage ratio of $8.686$, 0.12% different from exactly √2. Similarly, an increase of 6.000 dB corresponds to the power ratio is 106/10 ≈ $0.869$, about 0.5% different from 4.

Properties
The decibel is useful for representing large ratios and for simplifying representation of multiplicative effects, such as attenuation from multiple sources along a signal chain. Its application in systems with additive effects is less intuitive, such as in the combined sound pressure level of two machines operating together. Care is also necessary with decibels directly in fractions and with the units of multiplicative operations.

Reporting large ratios
The logarithmic scale nature of the decibel means that a very large range of ratios can be represented by a convenient number, in a manner similar to scientific notation. This allows one to clearly visualize huge changes of some quantity. See Bode plot and Semi-log plot. For example, 120 dB SPL may be clearer than "a trillion times more intense than the threshold of hearing".

Representation of multiplication operations
Level values in decibels can be added instead of multiplying the underlying power values, which means that the overall gain of a multi-component system, such as a series of amplifier stages, can be calculated by summing the gains in decibels of the individual components, rather than multiply the amplification factors; that is, log(A × B × C)= log(A) + log(B) + log(C). Practically, this means that, armed only with the knowledge that 1 dB is a power gain of approximately 26%, 3 dB is approximately 2× power gain, and 10 dB is 10× power gain, it is possible to determine the power ratio of a system from the gain in dB with only simple addition and multiplication. For example:
 * A system consists of 3 amplifiers in series, with gains (ratio of power out to in) of 10 dB, 8 dB, and 7 dB respectively, for a total gain of 25 dB. Broken into combinations of 10, 3, and 1 dB, this is: With an input of 1 watt, the output is approximately  Calculated precisely, the output is 1 W × 1025/10 ≈ 316.2 W. The approximate value has an error of only +0.4% with respect to the actual value, which is negligible given the precision of the values supplied and the accuracy of most measurement instrumentation.

However, according to its critics, the decibel creates confusion, obscures reasoning, is more related to the era of slide rules than to modern digital processing, and is cumbersome and difficult to interpret. Quantities in decibels are not necessarily additive,  thus being "of unacceptable form for use in dimensional analysis". Thus, units require special care in decibel operations. Take, for example, carrier-to-noise-density ratio C/N0 (in hertz), involving carrier power C (in watts) and noise power spectral density N0 (in W/Hz). Expressed in decibels, this ratio would be a subtraction (C/N0)dB = CdB − N0dB. However, the linear-scale units still simplify in the implied fraction, so that the results would be expressed in dB-Hz.

Representation of addition operations
According to Mitschke, "The advantage of using a logarithmic measure is that in a transmission chain, there are many elements concatenated, and each has its own gain or attenuation. To obtain the total, addition of decibel values is much more convenient than multiplication of the individual factors." However, for the same reason that humans excel at additive operation over multiplication, decibels are awkward in inherently additive operations: "if two machines each individually produce a sound pressure level of, say, 90 dB at a certain point, then when both are operating together we should expect the combined sound pressure level to increase to 93 dB, but certainly not to 180 dB!; suppose that the noise from a machine is measured (including the contribution of background noise) and found to be 87 dBA but when the machine is switched off the background noise alone is measured as 83 dBA. [...] the machine noise [level (alone)] may be obtained by 'subtracting' the 83 dBA background noise from the combined level of 87 dBA; i.e., 84.8 dBA.; in order to find a representative value of the sound level in a room a number of measurements are taken at different positions within the room, and an average value is calculated. [...] Compare the logarithmic and arithmetic averages of [...] 70 dB and 90 dB: logarithmic average = 87 dB; arithmetic average = 80 dB."

Addition on a logarithmic scale is called logarithmic addition, and can be defined by taking exponentials to convert to a linear scale, adding there, and then taking logarithms to return. For example, where operations on decibels are logarithmic addition/subtraction and logarithmic multiplication/division, while operations on the linear scale are the usual operations:
 * $$87\,\text{dBA} \ominus 83\,\text{dBA} = 10 \cdot \log_{10}\bigl(10^{87/10} - 10^{83/10}\bigr)\,\text{dBA} \approx 84.8\,\text{dBA}$$

\begin{align} M_\text{lm}(70, 90) &= \left(70\,\text{dBA} + 90\,\text{dBA}\right)/2 \\ &= 10 \cdot \log_{10}\left(\bigl(10^{70/10} + 10^{90/10}\bigr)/2\right)\,\text{dBA} \\ &= 10 \cdot \left(\log_{10}\bigl(10^{70/10} + 10^{90/10}\bigr) - \log_{10} 2\right)\,\text{dBA} \approx 87\,\text{dBA}. \end{align} $$ The logarithmic mean is obtained from the logarithmic sum by subtracting $$10\log_{10} 2$$, since logarithmic division is linear subtraction.

Fractions
Attenuation constants, in topics such as optical fiber communication and radio propagation path loss, are often expressed as a fraction or ratio to distance of transmission. In this case, dB/m represents decibel per meter, dB/mi represents decibel per mile, for example. These quantities are to be manipulated obeying the rules of dimensional analysis, e.g., a 100-meter run with a 3.5 dB/km fiber yields a loss of 0.35 dB = 3.5 dB/km × 0.1 km.

Perception
The human perception of the intensity of sound and light more nearly approximates the logarithm of intensity rather than a linear relationship (see Weber–Fechner law), making the dB scale a useful measure.

Acoustics
The decibel is commonly used in acoustics as a unit of sound power level or sound pressure level. The reference pressure for sound in air is set at the typical threshold of perception of an average human and there are common comparisons used to illustrate different levels of sound pressure. As sound pressure is a root-power quantity, the appropriate version of the unit definition is used:

L_p = 20 \log_{10}\!\left(\frac{p_{\text{rms}}}{p_{\text{ref}}}\right)\,\text{dB}, $$ where prms is the root mean square of the measured sound pressure and pref is the standard reference sound pressure of 20 micropascals in air or 1 micropascal in water.

Use of the decibel in underwater acoustics leads to confusion, in part because of this difference in reference value.

Sound intensity is proportional to the square of sound pressure. Therefore the sound intensity level can also be defined as:

L_p = 10 \log_{10}\!\left(\frac{I}{I_{\text{ref}}}\right)\,\text{dB}, $$

The human ear has a large dynamic range in sound reception. The ratio of the sound intensity that causes permanent damage during short exposure to that of the quietest sound that the ear can hear is equal to or greater than 1 trillion (1012). Such large measurement ranges are conveniently expressed in logarithmic scale: the base-10 logarithm of 1012 is 12, which is expressed as a sound intensity level of 120 dB re 1 pW/m2. The reference values of I and p in air have been chosen such that this corresponds approximately to a sound pressure level of 120 dB re 20 μPa.

Since the human ear is not equally sensitive to all sound frequencies, the acoustic power spectrum is modified by frequency weighting (A-weighting being the most common standard) to get the weighted acoustic power before converting to a sound level or noise level in decibels.

Telephony
The decibel is used in telephony and audio. Similarly to the use in acoustics, a frequency weighted power is often used. For audio noise measurements in electrical circuits, the weightings are called psophometric weightings.

Electronics
In electronics, the decibel is often used to express power or amplitude ratios (as for gains) in preference to arithmetic ratios or percentages. One advantage is that the total decibel gain of a series of components (such as amplifiers and attenuators) can be calculated simply by summing the decibel gains of the individual components. Similarly, in telecommunications, decibels denote signal gain or loss from a transmitter to a receiver through some medium (free space, waveguide, coaxial cable, fiber optics, etc.) using a link budget.

The decibel unit can also be combined with a reference level, often indicated via a suffix, to create an absolute unit of electric power. For example, it can be combined with "m" for "milliwatt" to produce the "dBm". A power level of 0 dBm corresponds to one milliwatt, and 1 dBm is one decibel greater (about 1.259 mW).

In professional audio specifications, a popular unit is the dBu. This is relative to the root mean square voltage which delivers 1 mW (0 dBm) into a 600-ohm resistor, or √1 mW×600 Ω≈ 0.775 VRMS. When used in a 600-ohm circuit (historically, the standard reference impedance in telephone circuits), dBu and dBm are identical.

Optics
In an optical link, if a known amount of optical power, in dBm (referenced to 1 mW), is launched into a fiber, and the losses, in dB (decibels), of each component (e.g., connectors, splices, and lengths of fiber) are known, the overall link loss may be quickly calculated by addition and subtraction of decibel quantities.

In spectrometry and optics, the blocking unit used to measure optical density is equivalent to −1 B.

Video and digital imaging
In connection with video and digital image sensors, decibels generally represent ratios of video voltages or digitized light intensities, using 20 log of the ratio, even when the represented intensity (optical power) is directly proportional to the voltage generated by the sensor, not to its square, as in a CCD imager where response voltage is linear in intensity. Thus, a camera signal-to-noise ratio or dynamic range quoted as 40 dB represents a ratio of 100:1 between optical signal intensity and optical-equivalent dark-noise intensity, not a 10,000:1 intensity (power) ratio as 40 dB might suggest. Sometimes the 20 log ratio definition is applied to electron counts or photon counts directly, which are proportional to sensor signal amplitude without the need to consider whether the voltage response to intensity is linear.

However, as mentioned above, the 10 log intensity convention prevails more generally in physical optics, including fiber optics, so the terminology can become murky between the conventions of digital photographic technology and physics. Most commonly, quantities called "dynamic range" or "signal-to-noise" (of the camera) would be specified in 20 log dB, but in related contexts (e.g. attenuation, gain, intensifier SNR, or rejection ratio) the term should be interpreted cautiously, as confusion of the two units can result in very large misunderstandings of the value.

Photographers typically use an alternative base-2 log unit, the stop, to describe light intensity ratios or dynamic range.

Suffixes and reference values
Suffixes are commonly attached to the basic dB unit in order to indicate the reference value by which the ratio is calculated. For example, dBm indicates power measurement relative to 1 milliwatt.

In cases where the unit value of the reference is stated, the decibel value is known as "absolute". If the unit value of the reference is not explicitly stated, as in the dB gain of an amplifier, then the decibel value is considered relative.

This form of attaching suffixes to dB is widespread in practice, albeit being against the rules promulgated by standards bodies (ISO and IEC), given the "unacceptability of attaching information to units" and the "unacceptability of mixing information with units". The IEC 60027-3 standard recommends the following format: Lx (re xref) or as Lx/x ref, where x is the quantity symbol and xref is the value of the reference quantity, e.g., LE (re 1 μV/m) = 20 dB or LE/(1 μV/m) = 20 dB for the electric field strength E relative to 1 μV/m reference value. If the measurement result 20 dB is presented separately, it can be specified using the information in parentheses, which is then part of the surrounding text and not a part of the unit: 20 dB (re: 1 μV/m) or 20 dB (1 μV/m).

Outside of documents adhering to SI units, the practice is very common as illustrated by the following examples. There is no general rule, with various discipline-specific practices. Sometimes the suffix is a unit symbol ("W","K","m"), sometimes it is a transliteration of a unit symbol ("uV" instead of μV for microvolt), sometimes it is an acronym for the unit's name ("sm" for square meter, "m" for milliwatt), other times it is a mnemonic for the type of quantity being calculated ("i" for antenna gain with respect to an isotropic antenna, "λ" for anything normalized by the EM wavelength), or otherwise a general attribute or identifier about the nature of the quantity ("A" for A-weighted sound pressure level). The suffix is often connected with a hyphen, as in "dBHz", or with a space, as in "dB HL", or enclosed in parentheses, as in "dB(sm)", or with no intervening character, as in "dBm" (which is non-compliant with international standards).

Voltage
Since the decibel is defined with respect to power, not amplitude, conversions of voltage ratios to decibels must square the amplitude, or use the factor of 20 instead of 10, as discussed above.

 * dBV : dB(VRMS) – voltage relative to 1 volt, regardless of impedance. This is used to measure microphone sensitivity, and also to specify the consumer line-level of −10 dBV, in order to reduce manufacturing costs relative to equipment using a +4 dBu line-level signal.

 * dBu or dBv : RMS voltage relative to $V = \sqrt{600 \, \Omega \cdot 0.001\,\text{W}} \approx 0.7746\,\text{V}$|undefined (i.e. the voltage that would dissipate 1 mW into a 600 Ω load). An RMS voltage of 1 V therefore corresponds to $$20\cdot\log_{10}\left ( \frac{1\,V_\text{RMS}}{\sqrt{0.6}\,V} \right )=2.218\,\text{dBu}.$$ Originally dBv, it was changed to dBu to avoid confusion with dBV. The v comes from volt, while u comes from the volume unit used in the VU meter. dBu can be used as a measure of voltage, regardless of impedance, but is derived from a 600 Ω load dissipating 0 dBm (1 mW). The reference voltage comes from the computation $V = \sqrt{R \cdot P}$ where $$R$$ is the resistance and $$P$$ is the power. In professional audio, equipment may be calibrated to indicate a "0" on the VU meters some finite time after a signal has been applied at an amplitude of +4 dBu. Consumer equipment typically uses a lower "nominal" signal level of −10 dBV. Therefore, many devices offer dual voltage operation (with different gain or "trim" settings) for interoperability reasons.  A switch or adjustment that covers at least the range between +4 dBu and −10 dBV is common in professional equipment.

 * dBm0s : Defined by Recommendation ITU-R V.574.; dBmV: dB(mVRMS) – voltage relative to 1 millivolt across 75 Ω. Widely used in cable television networks, where the nominal strength of a single TV signal at the receiver terminals is about 0 dBmV. Cable TV uses 75 Ω coaxial cable, so 0 dBmV corresponds to −78.75 dBW (−48.75 dBm) or approximately 13 nW.

 * dBμV or dBuV : dB(μVRMS) – voltage relative to 1 microvolt. Widely used in television and aerial amplifier specifications. 60 dBμV = 0 dBmV.

Acoustics
Probably the most common usage of "decibels" in reference to sound level is dB SPL, sound pressure level referenced to the nominal threshold of human hearing: The measures of pressure (a root-power quantity) use the factor of 20, and the measures of power (e.g. dB SIL and dB SWL) use the factor of 10.
 * dB SPL : dB SPL (sound pressure level) – for sound in air and other gases, relative to 20 micropascals (μPa), or $7.389$, approximately the quietest sound a human can hear. For sound in water and other liquids, a reference pressure of 1 μPa is used.  An RMS sound pressure of one pascal corresponds to a level of 94 dB SPL.
 * dB SIL : dB sound intensity level – relative to 10−12 W/m2, which is roughly the threshold of human hearing in air.
 * dB SWL : dB sound power level – relative to 10−12 W.
 * dBA, dBB, and dBC : These symbols are often used to denote the use of different weighting filters, used to approximate the human ear's response to sound, although the measurement is still in dB (SPL). These measurements usually refer to noise and its effects on humans and other animals, and they are widely used in industry while discussing noise control issues, regulations and environmental standards. Other variations that may be seen are dBA or dB(A). According to standards from the International Electro-technical Committee (IEC 61672-2013) and the American National Standards Institute, ANSI S1.4, the preferred usage is to write LA = x dB. Nevertheless, the units dBA and dB(A) are still commonly used as a shorthand for Aweighted measurements. Compare dBc, used in telecommunications.
 * dB HL : dB hearing level is used in audiograms as a measure of hearing loss. The reference level varies with frequency according to a minimum audibility curve as defined in ANSI and other standards, such that the resulting audiogram shows deviation from what is regarded as 'normal' hearing.
 * dB Q : sometimes used to denote weighted noise level, commonly using the ITU-R 468 noise weighting
 * dBpp : relative to the peak to peak sound pressure.
 * dBG : Gweighted spectrum

Audio electronics
See also dBV and dBu above.

 * dBm : dB(mW) – power relative to 1 milliwatt. In audio and telephony, dBm is typically referenced relative to a 600 Ω impedance, which corresponds to a voltage level of 0.775 volts or 775 millivolts.
 * dBm0 : Power in dBm (described above) measured at a zero transmission level point.
 * dBFS : dB(full scale) – the amplitude of a signal compared with the maximum which a device can handle before clipping occurs. Full-scale may be defined as the power level of a full-scale sinusoid or alternatively a full-scale square wave. A signal measured with reference to a full-scale sine-wave appears 3 dB weaker when referenced to a full-scale square wave, thus: 0 dBFS(fullscale sine wave) = −3 dBFS(fullscale square wave).
 * dBVU : dB volume unit
 * dBTP : dB(true peak) – peak amplitude of a signal compared with the maximum which a device can handle before clipping occurs. In digital systems, 0 dBTP would equal the highest level (number) the processor is capable of representing. Measured values are always negative or zero, since they are less than or equal to full-scale.

Radar

 * dBZ : dB(Z) – decibel relative to Z = 1 mm6⋅m−3: energy of reflectivity (weather radar), related to the amount of transmitted power returned to the radar receiver. Values above 20 dBZ usually indicate falling precipitation.
 * dBsm : dB(m2) – decibel relative to one square meter: measure of the radar cross section (RCS) of a target. The power reflected by the target is proportional to its RCS. "Stealth" aircraft and insects have negative RCS measured in dBsm, large flat plates or non-stealthy aircraft have positive values.

Radio power, energy, and field strength

 * dBc : relative to carrier – in telecommunications, this indicates the relative levels of noise or sideband power, compared with the carrier power. Compare dBC, used in acoustics.
 * dBpp : relative to the maximum value of the peak power.
 * dBJ : energy relative to 1 joule. 1 joule = 1 watt second = 1 watt per hertz, so power spectral density can be expressed in dBJ.
 * dBm : dB(mW) – power relative to 1 milliwatt. In the radio field, dBm is usually referenced to a 50 Ω load, with the resultant voltage being 0.224 volts.
 * dBμV/m, dBuV/m, or dBμ : dB(μV/m) – electric field strength relative to 1 microvolt per meter. The unit is often used to specify the signal strength of a television broadcast at a receiving site (the signal measured at the antenna output is reported in dBμV).
 * dBf : dB(fW) – power relative to 1 femtowatt.
 * dBW : dB(W) – power relative to 1 watt.
 * dBk : dB(kW) – power relative to 1 kilowatt.
 * dBe : dB electrical.
 * dBo : dB optical. A change of 1 dBo in optical power can result in a change of up to 2 dBe in electrical signal power in a system that is thermal noise limited.

Antenna measurements

 * dBi : dB(isotropic) – the gain of an antenna compared with the gain of a theoretical isotropic antenna, which uniformly distributes energy in all directions. Linear polarization of the EM field is assumed unless noted otherwise.
 * dBd : dB(dipole) – the gain of an antenna compared with the gain a half-wave dipole antenna. 0 dBd = 2.15 dBi
 * dBiC : dB(isotropic circular) – the gain of an antenna compared to the gain of a theoretical circularly polarized isotropic antenna. There is no fixed conversion rule between dBiC and dBi, as it depends on the receiving antenna and the field polarization.
 * dBq : dB(quarterwave) – the gain of an antenna compared to the gain of a quarter wavelength whip. Rarely used, except in some marketing material. 0 dBq = −0.85 dBi
 * dBsm : dB(m2) – decibel relative to one square meter: measure of the antenna effective area.
 * dBm−1 : dB(m−1) – decibel relative to reciprocal of meter: measure of the antenna factor.

Other measurements

 * dBHz : dB(Hz) – bandwidth relative to one hertz. E.g., 20 dBHz corresponds to a bandwidth of 100 Hz. Commonly used in link budget calculations. Also used in carrier-to-noise-density ratio (not to be confused with carrier-to-noise ratio, in dB).
 * dBov or dBO: dB(overload) – the amplitude of a signal (usually audio) compared with the maximum which a device can handle before clipping occurs. Similar to dBFS, but also applicable to analog systems. According to ITU-T Rec. G.100.1 the level in dBov of a digital system is defined as:  with the maximum signal power $$P_0=1.0$$, for a rectangular signal with the maximum amplitude $$x_\text{over}$$. The level of a tone with a digital amplitude (peak value) of $$x_\text{over}$$ is therefore $$L= -3.01\ \text{dBov}$$.
 * dBr : dB(relative) – simply a relative difference from something else, which is made apparent in context. The difference of a filter's response to nominal levels, for instance.
 * dBrn : dB above reference noise. See also dBrnC
 * dBrnC : dBrnC represents an audio level measurement, typically in a telephone circuit, relative to a -90 dBm reference level, with the measurement of this level frequency-weighted by a standard C-message weighting filter. The C-message weighting filter was chiefly used in North America.  The Psophometric filter is used for this purpose on international circuits.  See Psophometric weighting to see a comparison of frequency response curves for the C-message weighting and Psophometric weighting filters.
 * dBK : dB(K) – decibels relative to 1 K; used to express noise temperature.
 * dB/K : dB(K−1) – decibels relative to 1 K−1. — not decibels per kelvin: Used for the G/T factor, a figure of merit utilized in satellite communications, relating the antenna gain G to the receiver system noise equivalent temperature T.

Unpunctuated suffixes

 * dBA : see dB(A).
 * dBa : see dBrn adjusted.
 * dBB : see dB(B).
 * dBc : relative to carrier – in telecommunications, this indicates the relative levels of noise or sideband power, compared with the carrier power.
 * dBC : see dB(C).
 * dBD : see dB(D).
 * dBd : dB(dipole) – the forward gain of an antenna compared with a half-wave dipole antenna. 0 dBd = 2.15 dBi
 * dBe : dB electrical.
 * dBf : dB(fW) – power relative to 1 femtowatt.
 * dBFS : dB(full scale) – the amplitude of a signal compared with the maximum which a device can handle before clipping occurs. Full-scale may be defined as the power level of a full-scale sinusoid or alternatively a full-scale square wave. A signal measured with reference to a full-scale sine-wave appears 3 dB weaker when referenced to a full-scale square wave, thus: 0 dBFS(fullscale sine wave) = −3 dBFS(fullscale square wave).
 * dBG : G-weighted spectrum
 * dBi : dB(isotropic) – the forward gain of an antenna compared with the hypothetical isotropic antenna, which uniformly distributes energy in all directions. Linear polarization of the EM field is assumed unless noted otherwise.
 * dBiC : dB(isotropic circular) – the forward gain of an antenna compared to a circularly polarized isotropic antenna. There is no fixed conversion rule between dBiC and dBi, as it depends on the receiving antenna and the field polarization.
 * dBJ : energy relative to 1 joule. 1 joule = 1 watt second = 1 watt per hertz, so power spectral density can be expressed in dBJ.
 * dBk : dB(kW) – power relative to 1 kilowatt.
 * dBK :dB(K) – decibels relative to kelvin: Used to express noise temperature.
 * dBm : dB(mW) – power relative to 1 milliwatt.
 * dBm0 : Power in dBm measured at a zero transmission level point.
 * dBm0s : Defined by Recommendation ITU-R V.574.
 * dBmV : dB(mVRMS) – voltage relative to 1 millivolt across 75 Ω.
 * dBo : dB optical. A change of 1 dBo in optical power can result in a change of up to 2 dBe in electrical signal power in system that is thermal noise limited.
 * dBO : see dBov
 * dBov or dBO : dB(overload) – the amplitude of a signal (usually audio) compared with the maximum which a device can handle before clipping occurs.
 * dBpp : relative to the peak to peak sound pressure.
 * dBpp : relative to the maximum value of the peak power.
 * dBq : dB(quarterwave) – the forward gain of an antenna compared to a quarter wavelength whip. Rarely used, except in some marketing material. 0 dBq = −0.85 dBi
 * dBr : dB(relative) – simply a relative difference from something else, which is made apparent in context. The difference of a filter's response to nominal levels, for instance.
 * dBrn : dB above reference noise. See also dBrnC
 * dBrnC : dBrnC represents an audio level measurement, typically in a telephone circuit, relative to the circuit noise level, with the measurement of this level frequency-weighted by a standard C-message weighting filter. The C-message weighting filter was chiefly used in North America.
 * dBsm : dB(m2) – decibel relative to one square meter
 * dBTP : dB(true peak) – peak amplitude of a signal compared with the maximum which a device can handle before clipping occurs.
 * dBu or dBv : RMS voltage relative to $\sqrt{0.6}\,\text{V}\, \approx 0.7746\,\text{V}\, \approx -2.218\,\text{dBV}$.
 * dBu0s : Defined by Recommendation ITU-R V.574.
 * dBuV : see dBμV
 * dBuV/m : see dBμV/m
 * dBv : see dBu
 * dBV : dB(VRMS) – voltage relative to 1 volt, regardless of impedance.
 * dBVU : dB volume unit
 * dBW : dB(W) – power relative to 1 watt.
 * dBW·m−2·Hz−1 : spectral density relative to 1 W·m−2·Hz−1
 * dBZ : dB(Z) – decibel relative to Z = 1 mm6⋅m−3
 * dBμ : see dBμV/m
 * dBμV or dBuV : dB(μVRMS) – voltage relative to 1 microvolt.
 * dBμV/m, dBuV/m, or dBμ : dB(μV/m) – electric field strength relative to 1 microvolt per meter.

Suffixes preceded by a space

 * dB HL : dB hearing level is used in audiograms as a measure of hearing loss.
 * dB Q : sometimes used to denote weighted noise level
 * dB SIL : dB sound intensity level – relative to 10−12 W/m2
 * dB SPL : dB SPL (sound pressure level) – for sound in air and other gases, relative to 20 μPa in air or 1 μPa in water
 * dB SWL : dB sound power level – relative to 10−12 W.

Suffixes within parentheses

 * dB(A), dB(B), dB(C), dB(D), dB(G), and dB(Z) : These symbols are often used to denote the use of different weighting filters, used to approximate the human ear's response to sound, although the measurement is still in dB (SPL). These measurements usually refer to noise and its effects on humans and other animals, and they are widely used in industry while discussing noise control issues, regulations and environmental standards. Other variations that may be seen are dBA or dBA.

Other suffixes

 * dB-Hz : dB(Hz) – bandwidth relative to one hertz.
 * dB/K : dB(K−1) – decibels relative to reciprocal of kelvin
 * dBm−1 : dB(m−1) – decibel relative to reciprocal of meter: measure of the antenna factor.

 * mBm : mB(mW) – power relative to 1 milliwatt, in millibels (one hundredth of a decibel). 100 mBm = 1 dBm. This unit is in the Wi-Fi drivers of the Linux kernel and the regulatory domain sections.

title: Decibel


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Darwinism

Darwinism is a theory of biological evolution developed by the English naturalist Charles Darwin (1809–1882) and others, stating that all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual's ability to compete, survive, and reproduce. Also called Darwinian theory, it originally included the broad concepts of transmutation of species or of evolution which gained general scientific acceptance after Darwin published On the Origin of Species in 1859, including concepts which predated Darwin's theories. English biologist Thomas Henry Huxley coined the term Darwinism in April 1860.

Terminology
Darwinism subsequently referred to the specific concepts of natural selection, the Weismann barrier, or the central dogma of molecular biology. Though the term usually refers strictly to biological evolution, creationists have appropriated it to refer to the origin of life or to cosmic evolution, that are distinct to biological evolution. It is therefore considered the belief and acceptance of Darwin's and of his predecessors' work, in place of other concepts, including divine design and extraterrestrial origins.

English biologist Thomas Henry Huxley coined the term Darwinism in April 1860. It was used to describe evolutionary concepts in general, including earlier concepts published by English philosopher Herbert Spencer. Many of the proponents of Darwinism at that time, including Huxley, had reservations about the significance of natural selection, and Darwin himself gave credence to what was later called Lamarckism. The strict neo-Darwinism of German evolutionary biologist August Weismann gained few supporters in the late 19th century. During the approximate period of the 1880s to about 1920, sometimes called "the eclipse of Darwinism", scientists proposed various alternative evolutionary mechanisms which eventually proved untenable. The development of the modern synthesis in the early 20th century, incorporating natural selection with population genetics and Mendelian genetics, revived Darwinism in an updated form.

While the term Darwinism has remained in use amongst the public when referring to modern evolutionary theory, it has increasingly been argued by science writers such as Olivia Judson, Eugenie Scott, and Carl Safina that it is an inappropriate term for modern evolutionary theory. For example, Darwin was unfamiliar with the work of the Moravian scientist and Augustinian friar Gregor Mendel, and as a result had only a vague and inaccurate understanding of heredity. He naturally had no inkling of later theoretical developments and, like Mendel himself, knew nothing of genetic drift, for example.

In the United States, creationists often use the term "Darwinism" as a pejorative term in reference to beliefs such as scientific materialism. This is now also the case even in the United Kingdom.

Huxley

Huxley, upon first reading Darwin's theory in 1858, responded, "How extremely stupid not to have thought of that!"

While the term Darwinism had been used previously to refer to the work of Erasmus Darwin in the late 18th century, the term as understood today was introduced when Charles Darwin's 1859 book On the Origin of Species was reviewed by Thomas Henry Huxley in the April 1860 issue of the Westminster Review. Having hailed the book as "a veritable Whitworth gun in the armoury of liberalism" promoting scientific naturalism over theology, and praising the usefulness of Darwin's ideas while expressing professional reservations about Darwin's gradualism and doubting if it could be proved that natural selection could form new species, Huxley compared Darwin's achievement to that of Nicolaus Copernicus in explaining planetary motion:

These are the basic tenets of evolution by natural selection as defined by Darwin:

 * 1) More individuals are produced each generation than can survive.
 * 2) Phenotypic variation exists among individuals and the variation is heritable.
 * 3) Those individuals with heritable traits better suited to the environment will survive.
 * 4) When reproductive isolation occurs new species will form.

Other 19th-century usage
"Darwinism" soon came to stand for an entire range of evolutionary (and often revolutionary) philosophies about both biology and society. One of the more prominent approaches, summed in the 1864 phrase "survival of the fittest" by Herbert Spencer, later became emblematic of Darwinism even though Spencer's own understanding of evolution (as expressed in 1857) was more similar to that of Jean-Baptiste Lamarck than to that of Darwin, and predated the publication of Darwin's theory in 1859. What is now called "Social Darwinism" was, in its day, synonymous with "Darwinism"—the application of Darwinian principles of "struggle" to society, usually in support of anti-philanthropic political agenda. Another interpretation, one notably favoured by Darwin's half-cousin Francis Galton, was that "Darwinism" implied that because natural selection was apparently no longer working on "civilized" people, it was possible for "inferior" strains of people (who would normally be filtered out of the gene pool) to overwhelm the "superior" strains, and voluntary corrective measures would be desirable—the foundation of eugenics.

In Darwin's day there was no rigid definition of the term "Darwinism", and it was used by opponents and proponents of Darwin's biological theory alike to mean whatever they wanted it to in a larger context. The ideas had international influence, and Ernst Haeckel developed what was known as Darwinismus in Germany, although, like Spencer's "evolution", Haeckel's "Darwinism" had only a rough resemblance to the theory of Charles Darwin, and was not centred on natural selection. In 1886, Alfred Russel Wallace went on a lecture tour across the United States, starting in New York and going via Boston, Washington, Kansas, Iowa and Nebraska to California, lecturing on what he called "Darwinism" without any problems.

In his book Darwinism (1889), Wallace had used the term pure-Darwinism which proposed a "greater efficacy" for natural selection. George Romanes dubbed this view as "Wallaceism", noting that in contrast to Darwin, this position was advocating a "pure theory of natural selection to the exclusion of any supplementary theory." Taking influence from Darwin, Romanes was a proponent of both natural selection and the inheritance of acquired characteristics. The latter was denied by Wallace who was a strict selectionist. Romanes' definition of Darwinism conformed directly with Darwin's views and was contrasted with Wallace's definition of the term.

Contemporary usage
The term Darwinism is often used in the United States by promoters of creationism, notably by leading members of the intelligent design movement, as an epithet to attack evolution as though it were an ideology (an "ism") based on philosophical naturalism, atheism, or both. For example, in 1993, UC Berkeley law professor and author Phillip E. Johnson made this accusation of atheism with reference to Charles Hodge's 1874 book What Is Darwinism?. However, unlike Johnson, Hodge confined the term to exclude those like American botanist Asa Gray who combined Christian faith with support for Darwin's natural selection theory, before answering the question posed in the book's title by concluding: "It is Atheism."

Creationists use pejoratively the term Darwinism to imply that the theory has been held as true only by Darwin and a core group of his followers, whom they cast as dogmatic and inflexible in their belief. In the 2008 documentary film Expelled: No Intelligence Allowed, which promotes intelligent design (ID), American writer and actor Ben Stein refers to scientists as Darwinists. Reviewing the film for Scientific American, John Rennie says "The term is a curious throwback, because in modern biology almost no one relies solely on Darwin's original ideas... Yet the choice of terminology isn't random: Ben Stein wants you to stop thinking of evolution as an actual science supported by verifiable facts and logical arguments and to start thinking of it as a dogmatic, atheistic ideology akin to Marxism."

However, Darwinism is also used neutrally within the scientific community to distinguish the modern evolutionary synthesis, which is sometimes called "neo-Darwinism", from those first proposed by Darwin. Darwinism also is used neutrally by historians to differentiate his theory from other evolutionary theories current around the same period. For example, Darwinism may refer to Darwin's proposed mechanism of natural selection, in comparison to more recent mechanisms such as genetic drift and gene flow. It may also refer specifically to the role of Charles Darwin as opposed to others in the history of evolutionary thought—particularly contrasting Darwin's results with those of earlier theories such as Lamarckism or later ones such as the modern evolutionary synthesis.

In political discussions in the United States, the term is mostly used by its enemies. Biologist E. O. Wilson at Harvard University described the term as being "a rhetorical device to make evolution seem like a kind of faith, like 'Maoism [...] Scientists don't call it 'Darwinism'." In the United Kingdom, the term often retains its positive sense as a reference to natural selection, and for example British ethologist and evolutionary biologist Richard Dawkins wrote in his collection of essays A Devil's Chaplain, published in 2003, that as a scientist he is a Darwinist.

In his 1995 book Darwinian Fairytales, Australian philosopher David Stove used the term "Darwinism" in a different sense than the above examples. Describing himself as non-religious and as accepting the concept of natural selection as a well-established fact, Stove nonetheless attacked what he described as flawed concepts proposed by some "Ultra-Darwinists." Stove alleged that by using weak or false ad hoc reasoning, these Ultra-Darwinists used evolutionary concepts to offer explanations that were not valid: for example, Stove suggested that the sociobiological explanation of altruism as an evolutionary feature was presented in such a way that the argument was effectively immune to any criticism. English philosopher Simon Blackburn wrote a rejoinder to Stove, though a subsequent essay by Stove's protégé James Franklin suggested that Blackburn's response actually "confirms Stove's central thesis that Darwinism can 'explain' anything."

In more recent times, the Australian moral philosopher and professor Peter Singer, who serves as the Ira W. DeCamp Professor of Bioethics at Princeton University, has proposed the development of a "Darwinian left" based on the contemporary scientific understanding of biological anthropology, human evolution, and applied ethics in order to achieve the establishment of a more equal and cooperative human society in accordance with the sociobiological explanation of altruism.

Esoteric usage
In evolutionary aesthetics theory, there is evidence that perceptions of beauty are determined by natural selection and therefore Darwinian; that things, aspects of people and landscapes considered beautiful are typically found in situations likely to give enhanced survival of the perceiving human's genes.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Darwinism


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Doraemon

Doraemon (ドラえもん) is a Japanese manga series written and illustrated by Fujiko F. Fujio. The manga was first serialized in 1969. Its chapters were collected in 45 volumes published by Shogakukan from 1974 to 1996. The story revolves around an earless robotic cat named Doraemon, who travels back in time from the 22nd century to aid a boy named Nobita Nobi.

The manga spawned a media franchise. Three anime TV series have been adapted in 1973, 1979, and 2005. Additionally, Shin-Ei Animation has produced over forty animated films, including two 3D computer-animated films, all of which are distributed by Toho. Various types of merchandise and media have been developed, including soundtrack albums, video games, and musicals. The manga series was licensed for an English language release in North America, via Amazon Kindle, by a collaboration of Fujiko F. Fujio Pro with Voyager Japan and AltJapan Co., Ltd. The anime series was licensed by Disney for an English-language release in North America in 2014, and LUK International in Europe, the Middle East and Africa.

Doraemon was well-received by critics and became a hit in many Asian countries. It won numerous awards, including the Japan Cartoonists Association Award in 1973 and 1994, the Shogakukan Manga Award for children's manga in 1982, and the Tezuka Osamu Cultural Prize in 1997. By 2019, it has sold over 250 million copies worldwide, becoming one of the best-selling manga series of all time. The character of Doraemon has been viewed as a Japanese cultural icon, and was appointed as the first "anime ambassador" in 2008 by the country's Foreign Ministry.

Synopsis
Nobita Nobi is a ten-year-old Japanese school boy, who is kind-hearted and honest, but also lazy, unlucky, weak, gets bad grades and is bad at sports. One day, a blue robot cat from the 22nd century named Doraemon is sent back to the past by Nobita's future great-great grandson, Sewashi Nobi, to take care of Nobita so that his descendants can have a better life. Doraemon has a four-dimensional pocket in which he stores tools, inventions, and gadgets from the future to aid Nobita whenever he is faced with a problem. Although Doraemon is a cat robot, he has a fear of mice because of an incident where robotic mice chewed off his ears. This is why Doraemon lost his original yellow color and turned blue, from sadness.

Nobita has three main friends: Takeshi Goda (nicknamed Gian), Suneo Honekawa (Gian's sidekick), and Shizuka Minamoto, Nobita's best friend and love-interest. Gian is a strong, leading and domineering boy, but also loyal to his friends. Suneo is a wealthy and spoiled boy who uses his friendship with Gian to win the respect of other schoolmates. Shizuka is a gentle and kind girl who frequently plays with Nobita. Nobita has a crush on Shizuka; she is his prospective future wife (Nobita's future wife is initially Gian's younger sister). Although Gian and Suneo are Nobita's friends, they also typically bully and abuse him. Nobita normally responds by using Doraemon's gadgets to fight back against them, but Nobita has a tendency to get carried away with using the gadgets (or Gian and Suneo, if they steal it away), which typically results in unintended consequences for him and others.

In addition to Gian, Suneo, and Shizuka, Dorami and Hidetoshi Dekisugi are also recurring characters. Dorami is Doraemon's younger sister, and Dekisugi is a gifted student boy who as Shizuka's close friend, frequently attracts the jealousy of Nobita.

Development and themes
Doraemon is written and illustrated by Fujiko F. Fujio, the pen name of Japanese manga artist Hiroshi Fujimoto. According to Fujio, it was originally conceived following a series of three events: when searching for ideas for a new manga, he wished a machine existed that would come up with ideas for him, he tripped over his daughter's toy, and heard cats fighting in his neighborhood. To set up the plot and characters, he used some elements from his earlier manga series, Obake no Q-Tarō, which involve an living with humans, with a similar formula. Fujio said that the idea for Doraemon came after "an accumulation of trial and error", during which he finally found the most suitable style of manga to him. Initially, the series achieved little success as was well-known at the time, and only became a hit after its adaptation into an anime TV series and multiple feature films.

Doraemon is mainly aimed at children, so Fujio chose to create the character with a simple graphic style, based on shapes such as circles and ellipses. He used the same sequences of cartoons with regularity and continuity to enhance the reader's ease of understanding. In addition, blue, a characteristic color of Doraemon, was chosen as the main color in magazine publications, which used to have a yellow cover and red title. Set in Tokyo, the manga reflected parts of Japan's society, such as the class system and the "ideal" of Japanese childhood. Problems, if occur, were resolved in a way so as not to rely on violence and eroticism, and the stories were integrated with the concept of environmentalism. The manga also insisted on the ethical values of integrity, perseverance, courage, family and respect.

In order to underline the crucial role of the young generation in society, the manga's creator chose to have the act carried out in a "children's domain" where young people can live with happiness, freedom and power without adult's interference. As Saya S. Shiraishi noted, the existence of the "domain" helped Doraemon to have a strong appeal in various Asian countries. During Doraemon 's development, Fujio did not express a change in characters; he said, "When a manga hero become a success, the manga suddenly stops being interesting. So the hero has to be like the stripes on a barber pole; he seems to keep moving upward, but actually he stays in the same place."

According to Zensho Ito, Fujio's former student, the "length" of time in the universe is one of the ideas that inspired Fujio to make Doraemon. Frequently displayed in its stories is Nobita's desire to control time, and there exist time-control gadgets that he uses to satisfy that desire, particularly the "Time Machine", which lies in his desk drawer. Unlike Western works on science fiction, the manga did not explain the theory nor the applied technology behind these tools, but instead focusing on how the characters exploit their advantages, making it more children-friendly.

Origin of the name
The name "Doraemon" can be roughly translated to "stray". Unusually, the name is written in a mixture of two Japanese scripts: Katakana (ドラ) and Hiragana (えもん). "Dora" derives from, and is a corruption of nora (stray), while "-emon" (in kanji 右衛門) is an old-fashioned suffix for male names (for example, as in Ishikawa Goemon). Nobita's home address in Tsukimidai ("moon-view-heights"), Nerima refers to Fujimidai ("Fuji-view-heights"), where Osamu Tezuka's residence and animation studio is based. The name "Nobita Nobi" refers to "nobi nobi", meaning "the way a young child grows up free, healthy, and happy, unrestrained in any sense".

Gadgets
Gadgets, or, are Doraemon's tools from the future, usually used to help the characters. Fujio said that Doraemon has a total of 1,293 gadgets; according to a 2004 analysis by Yasuyuki Yokoyama of Toyama University, there are 1,963 gadgets found in 1,344 sketches. The most important gadgets include "Take-Copter", a small piece of headgear made out of bamboo that can allow its users to fly; "Time Machine", a machine used for time travel; "Anywhere Door", a pink-colored door that allows people to travel according to the thoughts of the person who turns the knob; "Time Kerchief", a handkerchief which can turn an object new or old or a person young or old; "Translator Tool", a cuboid jelly that allow one to converse in any language; and "Designer", a camera used to instantly dress-up the user.

Saya S. Shiraishi wrote that most of the gadgets were "an impressive testimony to the standards of quality control and innovation that exist in the twenty-second century". The gadgets were an essential part of the series so as to reflect a positive point of view about the association of technology in children, and to express the wishes of modern society.

Conclusion
The series ceased its original run in 1994 and was not given a ending before Fujimoto's death in 1996; this has since aroused numerous urban legends throughout the years. One of the most well-known "endings" of the manga was by an amateur manga cartoonist under the pen name "Yasue T. Tajima", first appeared on the Internet in 1998 and made up into a manga in 2005. The story takes place when Doraemon's battery dies, and Nobita later grows up becoming a robot engineer, potentially revive Doraemon and live a happy life. Tajima issued an apology in 2007, and the profits were shared with Shogakukan and the copyright owner, Fujiko F. Fujio Pro.

Ryūichi Yagi and Takashi Yamazaki, the directors of Stand by Me Doraemon, confirmed that it had only one opening, while the ending has been rewritten several times. Because of this, Shogakukan had to clarify that only if the marriage of Nobita and Shizuka is finalized will the mission be accomplished, and then Doraemon will return to the future.

Manga
In December 1969, the Doraemon manga appeared in six different children's monthly magazines published by Shogakukan: Yoiko, Yōchien, Shogaku Ichi-nensei, Shogaku Ni-nensei, Shogaku San-nensei, and Shogaku Yo-nensei. The magazines were aimed at children from nursery school to fourth grade. In 1973, two other magazines, Shogaku Go-nensei and Shogaku Roku-nensei (aimed at fifth-grade and sixth-grade students respectively), started publishing the manga. In 1977, CoroCoro Comic was launched as the flagship magazine of ''Doraemon. ''

Since the debut of Doraemon in 1969, the stories have been selectively collected into forty-five volumes that were published under Shogakukan's Tentōmushi Comics (てんとう虫コミックス) imprint from July 31, 1974, to April 26, 1996. These volumes are collected in the Takaoka Central Library in Toyama, Japan, where Fujio was born. Between April 25, 2005, and February 28, 2006, Shōgakukan published a series of five manga volumes under the title Doraemon Plus (Doraemon+), featuring short stories which did not appear in the forty-five original volumes; a sixth volume, the first volume in eight years, was published on December 1, 2014. Additionally, 119 unpublished stories were compiled into six colored-manga volumes under the title Doraemon Kara Sakuhin-shu, published from July 17, 1999, to September 2, 2006. Between July 24, 2009, and September 25, 2012, Shogakukan published a master works collection consisting of twenty volumes with all 1,345 stories written by Fujio. In December 2019, on the 50th anniversary of Doraemon, a "Volume 0" was published by Shogakukan featuring six different versions of Doraemon's first appearance.

There have been two series of bilingual, Japanese and English, volumes of the manga by Shogakukan English Comics under the title Doraemon: Gadget Cat from the Future, and two audio versions. The first series has ten volumes and the second one has six. 21st Century Publishing House released bilingual English-Chinese versions in Mainland China, and Chingwin Publishing Group released bilingual English-Chinese versions in Taiwan.

In July 2013, Fujiko F. Fujio Pro announced that they would be collaborating with ebook publisher Voyager Japan and localization company AltJapan Co., Ltd. to release an English-language version of the manga in full color digitally via the Amazon Kindle platform in North America. Shogakukan released the first volume in November 2013; by 2016, a total of 200 volumes have been published. This English version incorporates a variety of changes to character names; Nobita is "Noby", Shizuka is "Sue", Suneo is "Sneech", and Gian is "Big G", while dorayaki is "Yummy Bun/Fudgy Pudgy Pie". Also, by 2016, four volumes of the manga have been published in English in print by Shogakukan Asia.

Shogakukan started digital distribution of all forty-five original volumes throughout Japan from July 16, 2015.

Long Stories
Doraemon's Long Tales is the core of the work, as is Doraemon Short Stories. Doraemon's Long Tales is a manga and movie series ongoing since 1979, featuring longer and continuous narratives about the characters' adventures into various lands of science fiction and fantasy. Long Stories manga series consists of twenty-four tankōbon volumes published from 1983 to 2004.

Spin-offs
Several spin-off manga series of Doraemon have been made. The Doraemons, a manga illustrated by Michiaki Tanaka based on Doraemon, was published by Shogakukan in six tankōbon volumes from 1996 to 2001. Between 1997 and 2003, Shogakukan also published fifteen volumes of The Doraemons Special, created by Yukihiro Mitani and Masaru Miyazaki as a complement part of The Doraemons, including twelve from the main series and three from the Robot Training School Edition. Dorabase, a baseball-themed manga written and illustrated by Mugiwara Shintarō, is another spin-off of Doraemon; twenty-three volumes of the manga were published by Shogakukan from April 26, 2001, to October 28, 2011.

Anime
The first attempt of a Doraemon animated series was in 1973, by Nippon Television. After a January 1973 pilot named Doraemon Mirai Kara Yattekuru, twenty-six episodes, each with two segments, were broadcast on Nippon TV from April 1 to September 30 of the same year. The series was directed by Mitsuo Kaminashi with voice cast from Aoni Production; the character Doraemon was voiced by Kōsei Tomita, then later by Masako Nozawa. Later in the series, the animation studio, Nippon TeleMovie Productions, went bankrupt, and the masters were sold off or destroyed. The series was re-aired on Nippon TV and several local stations until 1979, when Shogakukan requested Toyama Television to cease broadcasting. Some of the segments were found in the archives of Imagica in 1995, and some others were recovered by Jun Masami in 2003. As of 2013, 21 of 52 segments are known to survive, two of which have no audio.

Doraemon remained fairly exclusive in manga form until 1979 when a animation studio, Shin-Ei Animation (now owned by TV Asahi) produced an animated second attempt of Doraemon. The series aired on TV Asahi from April 2, 1979. Ryo Motohira served as chief director from 1981, and Tsutomu Shibayama from 1984. Eiichi Nakamura served as director of character designer, while Shunsuke Kikuchi was the composer. Nobuyo Ōyama voiced Doraemon in the series; because of this, in Asia, this version is sometimes referred to as the Ōyama Edition. In total, 1,787 episodes were produced and released in VHS and DVD by Toho. On April 15, 2005, a major renewal was carried out, including the replacement of voice actors and staff, and updated character designs (Doraemon (2005 TV series)). The third series is sometimes referred to in Asia as the Mizuta Edition, as a tribute for the voice actress for Doraemon, Wasabi Mizuta. It was released in DVD on February 10, 2006 under the title New TV-ban Doraemon with Shogakukan Video banner.

In May 2014, TV Asahi Corporation announced an agreement with The Walt Disney Company to bring the 2005 series to the Disney XD television channel and Disney Channel in the United States beginning in the summer of that year. Besides using the name changes that were used in AltJapan's English adaptation of the original manga, other changes and edits have also been made to make the show more relatable to an American audience, such as Japanese text being replaced with English text on certain objects like signs and graded papers, items such as yen notes being replaced by US dollar bills, and the setting being changed from Japan to the United States. Initial response to the edited dub was positive. The Disney adaptation began broadcast in Japan on Disney Channel from February 1, 2016. The broadcast offered the choice of the English voice track or a newly recorded Japanese track by the Japanese cast of the 2005 series.

The anime has also been aired in over sixty countries worldwide. It premiered in Thailand in 1982, the Philippines in 1999, India in 2005, and Vietnam in 2010. Other Asian countries that broadcast the series include China, Hong Kong, Singapore, Taiwan, Malaysia, Indonesia, and South Korea. The series is licensed in EMEA regions by LUK International; it premiered in Spain in 1993 and France in 2003. It has also been distributed in South American countries, including Brazil, Colombia, and Chile. In 2017, POPS Worldwide, a Vietnamese multimedia company, collaborated with TV Asahi to release the anime series on YouTube and other digital platforms.

Films
By 2024, there have been 43 annual feature-length animated films produced by Shin-Ei Animation and released by Toho. The first twenty-five films are based on the 1979 anime, while the rest are based on the 2005 anime. Unlike the anime and manga series, the films are more action-adventure oriented, taking the familiar characters of Doraemon and placing them in a variety of exotic and perilous settings.

A 3D computer animated film, Stand by Me Doraemon, debuted in Japan on August 8, 2014. Directed by Takashi Yamazaki and Ryūichi Yagi, it combines elements from the short stories of the manga series: "All the Way from the Country of the Future", "Imprinting Egg", "Goodbye, Shizuka-chan", "Romance in Snowy Mountain", "Nobita's the Night Before a Wedding", and "Goodbye, Doraemon ..." into a new complete story, from the first time Doraemon came to Nobita's house to Doraemon bidding farewell to Nobita. The film was a box office success, grossing $183.4 million worldwide. A sequel, Stand by Me Doraemon 2, also directed by Yamazaki and Yagi, was released on November 20, 2020.

Short films, OVA and crossover
Several Doraemon short films were produced and released between 1989 and 2004. These include 2112: The Birth of Doraemon, a film about the life of Doraemon from birth before coming to Nobita; Doraemon: Nobita's the Night Before a Wedding, a film about the events related to the marriage of Nobita and Shizuka; The Day When I Was Born and Doraemon: A Grandmother's Recollections, the films about the relationship between Nobita and his parents along with his grandmother. Other short films focus on Dorami and The Doraemons. In 1981, Toho released What Am I for Momotaro, a film about Momotarō, the hero of Japanese folklore.

In 1994, an educational OVA was made, titled Doraemon: Nobita to Mirai Note, where the main characters express the hope for a better Earth. The OVA was released in DVD along with the 13th issue of Fujiko F. Fujio Wonderland magazine in September 2004. A crossover episode of Doraemon with AIBOU: Tokyo Detective Duo aired on TV Asahi on November 9, 2018.

Music
The soundtrack of the 1973 anime series was composed by Nobuyoshi Koshibe, who also arranged the opening theme song "Doraemon" (ドラえもん) and the ending theme song "Doraemon Rumba" (ドラえもん ルンバ), both performed by Harumi Naitō. For the 1979 anime, Shunsuke Kikuchi was the composer, who arranged "Doraemon no Uta" (ドラえもんのうた); it had been performed by numerous singers, including Kumiko Ōsugi and Satoko Yamano. When the anime got a reboot in 2005, Kan Sawada was the composer of the series. There are four other opening themes, including an instrumental version of "Doraemon no Uta" performed by Twelve Girls Band; "Hagushichao" performed by Rimi Natsukawa; "Yume wo Kanaete Doraemon", the opening theme broadcast from 2007 to 2018; and "Doraemon" performed by Gen Hoshino, broadcast since October 2019.

Numerous collections of theme songs of the anime series and feature films were initially available in cassettes. Since the 1990s, Doraemon songs have been released in CD, under the type of singles and compilation albums. Soundtracks of Doraemon feature films have been released by Nippon Columbia since 2001 in the album series "Doraemon Soundtrack History" (ドラえもんサウンドトラックヒストリー).

Musical shows
Doraemon has been adapted into a musical, titled Doraemon the Musical: Nobita and the Animal Planet (舞台版ドラえもん のび太とアニマル). Based on the 1990 anime film of the same name, it debuted at Tokyo Metropolitan Art Space on September 4, 2008, running through September 14. Shoji Kokami was the director and writer, Makoto Sakamoto played Nobita and Reiko Suho as Shizuka; Jaian and Suneo were portrayed by Tomohiro Waki and Kensaku Kobayashi, respectively; Wasabi Mizuta voiced Doraemon. The musical was later revived and ran at Sunshine Theater, Tokyo from March 26 to April 2, 2017, then later in other prefectures including Fukuoka, Osaka, Miyagi and Aichi. The 2017 revival is also directed and written by Kokami, with Mizuta reprising her role; Nobita, Shizuka, Jaian and Suneo were played by Yuuchi Ogoe, Hina Higuchi, Koki Azuma and Shō Jinnai, respectively.

Video games
Many Japanese-only video games based on Doraemon have been developed. For instance, in 1983, Bandai developed, an arcade game inspired by Pac-Man. Doraemon, a NES video game made by Hudson Soft, was released on December 12, 1986, and became one of the best-selling games of that year in Japan with over 1.15 million copies sold. On December 6, 2007, Sega published Doraemon Wii, the first Doraemon video game released on Wii. Doraemon can also be seen in Namco's Taiko no Tatsujin rhythm game series, such as in Taiko no Tatsujin: Sesson de Dodon ga Don! (2017). The first Doraemon game to receive a Western release was Doraemon Story of Seasons (2019). Card games with Doraemon themes have also been made in several special occasions, sometimes to exploit the popularity of feature films. In 2016, a special edition of Uno about the series' characters was released exclusively in Japan, as a result of a cooperation between Asatsu-DK and Mattel.

Merchandise
In Japan, the Doraemon merchandising rights belong to Shogakukan-Shueisha Productions, which has produced and distributed a wide range of products under its brand, such as toys, food, stationery, action figures,, shoes, clothing, and others. Several companies have collaborated on the creation and distribution of products on the series and its characters, including Sanrio, Converse, Moleskine, and ESP Guitars, which has made guitars decorated with Doraemon characters; a further partnership of Doraemon with Uniqlo led to a line of clothing designed by Takashi Murakami. The Doraemon franchise has also collaborated with various Japanese brands, including Tsi Groove & Sports's Jack Bunny!! golf apparel brand,  Unicharm's MamiPoko diaper brand, and the video games LINE Pop 2, Monster Strike, and Granblue Fantasy. Viz Media owns the Doraemon merchandising rights in North and Latin America, which has developed Doraemon-themed clothing and collectibles in collaboration with retail chain Hot Topic, and themed Happy Meals in a 2015 collaboration with McDonald's. Viz Media Europe (now Crunchyroll EMEA) manages the merchandising in Europe except Spain and Portugal; LUK International has obtained licenses in these two countries.

Characters from Doraemon have been used in advertising through specific agreements with Shogakukan. For instance, following the Cool Japan initiative promoted by the Japanese government, Sharp Corporation produced a series of commercials featuring the characters of Doraemon and Nobita, which were broadcast in several ASEAN countries. In late 2011, Shogakukan and Toyota Motor Corporation joined forces to create a series of live-action commercials as part of Toyota's ReBorn ad campaign, which depicted the manga's characters two decades after being grown up, where Hollywood actor Jean Reno played Doraemon.

General
Doraemon is considered one of the best-known manga of all time, a true Japanese cultural icon, and an essential part of family life of the Japanese post-war generation. Akihiro Motoyama observed that "mothers who watched the movies when they were children are now taking their own children to see them". It was also commercially successful: over 108 million books were sold in Japan by 1996. The 1979 and 2005 anime series also achieved high ratings on television. With the film Doraemon: Nobita's Secret Gadget Museum, the Doraemon anime film series reached 100 million tickets sold at the Japanese box office, surpassing Godzilla as the highest-grossing film franchise in Japan. By 2015, it had sold over 103 million tickets, and was the largest franchise by numbers of admissions in the country.

Doraemon was also a hit in Asia in general, and was considered one of the typical cases of Japanese soft power, although it was published without a license in some countries. The anime television series is available in over 60 countries, and reportedly getting high ratings in at least 30 countries. However, Doraemon was less successful in Western countries, because it was viewed as a children-only series, and there were some tight restrictions about publishing manga and broadcasting anime series there. The manga has sold over 170 million copies worldwide by 2012, and 250 million by 2019. Estimates show that Doraemon has generated at least more than US$4.3 billion in merchandise sales by 2019, and over $1.7 billion from anime feature films by 2020, making it one of the highest-grossing media franchises of all time.

Outside Japan, Doraemon achieved particular success in Vietnam, with a record-breaking 40 million copies sold by 2006. The manga was first launched there in 1992 by Kim Đồng Publishing House, but the copyright from Shogakukan was not fully acquired until 1996. In 1993, the Vietnamese Ministry of Culture considered the manga's publication to be "an impactful event for the improvement of children, youth and adult's likings ... [Doraemon] is a comprehensively educational book series which has the effect of developing children's personality". Doraemon is now a cultural icon in Vietnam, having featured in many cultural events.

Critical response and analysis
Doraemon received favorable reviews. Mark Schilling wrote, "For kids whose lives are often so regulated, Doraemon represents a welcome breath of freedom and a glimpse of a funnier, friendlier world where all dreams, even foolish ones, can come true." Italian writer Massimo Nicora wrote that the manga "can be interpreted as a type of book that criticizes, with irony, the omnipotence of science that pretends to solve every problem with its tools", alluding to the fact that Doraemon's gadgets often end up making the problems even worse than they initially were, more than anything else. He added that it represents "the metaphor of the childish imagination, which always manages to find the most bizarre and original solutions, in a continuous game of transformation of reality".

Some critics considered that Nobita's flawed personality and modest background is different from the special or extraordinary characteristics usually seen in other typical anime and manga protagonists; this portrayal has been seen as reasons of its appeal as well as the contrary, especially in the United States. According to the Italian Parents Movement (Moige), in the manga, "the lazy Nobita does not know any kind of appreciable evolution", though there are still good points including "the criticism of bullying, the goodness that transpires from the little Nobita and the positive figure of Shizuka".

In his 2000 article, Leo Ching explained that the success of Doraemon in Asia was because it had reflected the Asian values such as imagination and responsibility, the same reason that Oshin, another Japanese cultural export, became well-known there. On the other hand, according to an analysis by Anne Allison, professor of cultural anthropology at Duke University, the strong point of it was not the variety of the gadgets, but the relationship between Doraemon and Nobita, which was particularly appreciated. Jason Thompson praised the "silly situations" and "old fashioned, simple artwork", with Doraemon's expression and comments adding to the "surrounding elementary-school mischief". On the manga's 50th anniversary, an op-ed published on Asahi Shimbun stated that the manga "has already become a contemporary classic".

Awards, accolades and public recognition
Doraemon has received numerous accolades. It won the Japan Cartoonists Association Award twice in 1973 and 1994, the former for Excellence Award while the latter for Minister of Education, Science and Technology Award. In 1982, it received the first Shogakukan Manga Award for children's manga. In 1997, the manga won the Grand Prize at the first Tezuka Osamu Cultural Prize. The 1979 series won the award from the Japanese Agency for Cultural Affairs four times for best television series in 1984, 1985, 1988 and 1989.

A 2006 poll among 80,000 Japanese fans for the 10th anniversary of the Japan Media Arts Festival placed Doraemon at fifth among the top ten best manga of all time. The 2005 and 2006 surveys conducted by TV Asahi found the Doraemon anime ranked fifth and third, respectively, among the 100 most favorite anime series of all time. In 2010, a survey conducted by researchers of Tokyo Polytechnic University found that most responders considered Doraemon, along with Dragon Ball franchise, to be the anime series that represents Cool Japan. In a 2013 survey, Doraemon was found to be the best anime recommended for foreign people.

Criticisms
Doraemon has been blamed for having a negative impact on children, due to the controversial traits of the characters in the anime. The character has received criticism in China, where some media outlets considered Doraemon to be a politically subversive character and that it was a tool of Japan's "cultural invasion". Some education groups in Taiwan demanded the anime to be banned, as the plot involve bullying which would encourage campus bullying. In 2016, a resolution to ban Hindi dubbed Doraemon anime series was submitted in Pakistan. Around the same time, legal notices were served against several companies in India, targeting Doraemon and Crayon Shin-chan for bans (which did not materialize), as having an adverse effect on children. Disney Channel India, the regional broadcaster of the anime, was banned in Bangladesh and Pakistan citing non-availability of localized dubs for content including Doraemon.

Cultural impact and legacy
The Doraemon manga has inspired many other mangakas; these include Eiichiro Oda, the creator of One Piece with the idea of "Devil Fruits", and Masashi Kishimoto, the creator of Naruto, who showed interest in drawing characters from anime shows during his childhood, including Doraemon. The manga has also been mentioned in Gin Tama and Great Teacher Onizuka. The character Doraemon is considered one of the cultural icons in Japan, and one of the most well-known characters in manga history; some critics compared his notability with Mickey Mouse and Snoopy. Mark Schilling noted that Doraemon's "Take-Copter" is familiar among Japanese people "just as Snoopy's biplane is familiar to most Americans".

On April 22, 2002, on the special issue of Asian Hero in Time magazine, Doraemon was the only anime character to be named one of the twenty-two Asian Heroes, and was described as "The Cuddliest Hero in Asia". A 2007 poll by Oricon shown that Doraemon was the second-strongest manga character ever, behind only Son Goku of Dragon Ball. Doraemon is also referred as something with the ability to satisfy all wishes.

In 2005, the Taiwan Society of New York selected Doraemon as a culturally significant work of Japanese otaku pop-culture in its exhibit Little Boy: The Arts of Japan's Exploding Subculture, curated by renowned artist Takashi Murakami. In 2008, the Japanese Ministry of Foreign Affairs appointed Doraemon as the first anime cultural ambassador; a Ministry spokesperson explained the decision as an attempt to help people in other countries understand Japanese anime better and to deepen their interest in Japanese culture. On September 3, 2012, Doraemon was granted official residence in the city of Kawasaki, Kanagawa, one hundred years before he was born. In the same year, Hong Kong celebrated the birthday of Doraemon 100 years early with a series of displays of the character. In April 2013, Doraemon was chosen as Japan's ambassador in Tokyo's bid to host the 2020 Summer Olympics and 2020 Summer Paralympics. He appeared in the 2016 Summer Olympics closing ceremony to promote the 2020 Summer Olympics in Tokyo.

A Fujiko F. Fujio museum opened in Kawasaki on September 3, 2011, featuring Doraemon as the star of the museum. The National Museum of Singapore held a time-travelling exhibition in October 2020 as a tribute to the manga. After the 2011 Tōhoku earthquake and tsunami, Shogakukan released an earthquake survival guidebook, which included the main cast of the Doraemon manga series. TV Asahi launched the Doraemon Fund charity fund to raise money for natural disasters in 2004, and in 2011. In 2020, Mumbai's Sion Friends Circle group distributed food and books to kids using mascots, one being Doraemon, to help during the COVID-19 pandemic. In Vietnam, a Doraemon scholarship fund was established in 1996, and the Doraemon character has been used for education of traffic safety. Doraemon 's creator, Fujiko F. Fujio, received the Culture Fighter Medal from the Vietnamese Ministry of Culture in 1996 for his contributions to young education through the manga.

Many prominent figures have been nicknamed after the cast of Doraemon: politician Osamu Fujimura is known as the "Doraemon of Nagatacho" due to his figure and warm personality, and sumo wrestler Takamisugi was nicknamed "Doraemon" because of his resemblance to the character. In 2015, a group of people in a drought-affected village in northern Thailand used a Doraemon toy to complete a rain-ritual, in order to avoid controversies that would occur by using real animals.

A parody of Doraemon created by Hikari Fujisaki, titled Nozoemon, was first serialized in Nihon Bungeisha's Comic Heaven magazine in September 2014, with the compiled book volume released on June 9, 2015; however, it was discontinued in August 2015 due to content issues.

title: Doraemon