Noise

Noise is a term for distortions in a signal. There are many different natural causes of noise: e.g. so-called 'thermal' noise, caused by the random motion of electrons in the conductors of a circuit; noise from the electro-magnetic radiation produced by natural phenomena such as lightning, solar radiation; etc.

Interference is the term often used for the subset of noise which is not from natural sources, but comes from other electrical systems.

Noise can occasionally be useful, e.g. as input to a random number generator.