Noise means a unwanted level of random interference added to a signal.
In common sense, the word noise means fuss, sound or unwanted noise. In electronics noise can be associated with acoustic perception, such a "wheezing" characteristic (white noise) or to "drizzle" in the poor reception of a television signal. Similarly the grain of a photo, when evident, also has the effect of noise. In signal processing, noise can be understood as a sign meaningless (random), it is important to the signal/noise ratio in communication. In information theory the noise is considered as information carrier.