n. ~ Computing · A process that reduces the amount of space necessary for data to be stored or transmitted.
'Compression' is often used to describe the process of compacting and extracting the information, although the term can be used to distinguish the first phase from the second phase, which is called decompression. The digital image formats JPEG and GIF both use compression to minimize file size.
Compression may be described as lossless and lossy. Lossless compression ensures that the uncompressed version is identical to the original; no information has been lost. Lossy compression results in some difference between the original and an uncompressed version. In general, lossy compression may produce a smaller file size. The GIF file format incorporates a compression algorithm that is lossless for images that contain fewer than 256 colors; images with more colors are reproduced with a limited palette. The JPEG format can, in theory, be configured to have varying degrees of loss, including a lossless option.