Noise is random variation in a signal, for example errors in measurements of the position of a moving object.
Noise is a signal produced by a stochastic process, mostly unwanted random addition to a signal. It is called noise as a generalization of the acoustic noise ("static") heard when listening to a weak radio transmission with significant electrical noise.
In signal processing or computing noise can be considered random unwanted data without meaning; that is, data that is not being used to transmit a signal, but is simply produced as an unwanted by-product of other activities. "Signal-to-noise ratio" (SNR) is sometimes used to refer to the ratio of useful to irrelevant information in an exchange.
Noise is usually uncorrelated and have a specific distribution that describes it (uniform, Gaussian, etc). The color of a noise signal is generally understood to be some broad characteristic of its power spectrum. Different "colors" of noise have significantly different properties. The practice of naming kinds of noise after colors started with "white noise", a signal whose spectrum has equal power within any equal interval of frequencies. That name was given by analogy with "white light", which was assumed to have such a "flat" power spectrum over the visible range. Other color names, like "pink", "red", and "blue" were then given to noise with other spectral profiles; often (but not always) in reference to the color of light with similar spectra. Some of those names have standard definitions in certain disciplines, while others are very informal and poorly defined.
Usage:
The tag noise can be used for programming related questions to remove/filter noise from a system and other related questions. Please avoid theoretical and physics based noise related questions on stackoverflow, https://physics.stackexchange.com/ is another stackexchange site where you can ask such theoretical and physics based questions.
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