Dither is an intentionally applied form of noise used to randomize quantization error, preventing large-scale patterns such as color banding in images. Dither is routinely used in processing of both digital audio and digital video data, and is often one of the last stages of audio production to compact disc.
Read more about Dither: Etymology, In Digital Processing and Waveform Analysis, Digital Audio, Digital Photography and Image Processing, In Optical Fiber Systems