In
signal processing,
data compression,
source coding, or
bit-rate reduction involves
encoding information using fewer
bits than the original representation. Compression can be either
lossy or
lossless.
Lossless compression reduces bits by identifying and eliminating
statistical redundancy. No information is lost in lossless compression.
Lossy compression reduces bits by identifying unnecessary information and removing it. The process of reducing the size of a data file is referred to as data compression. In the context of data transmission, it is called source coding (encoding done at the source of the data before it is stored or transmitted) in opposition to channel coding.