The encoding of digital information in order to store it using fewer bits.
Compression is encoding of digital information in order to store it using fewer bits. It can be loss-less, in which all of the original information can be decoded to its original state, or lossy, in which some information is discarded as part of the encoding process. Compression/decompression can occur as a standalone operation (static to disk) or on-the-fly (in memory) at a potential performance cost, as compressed data must be decompressed in order to access it.
Some examples of compression are:
- that built into image or raster data formats (ie jpg or lzw compressed tiff files)
- database compression (note this is different than compaction)
- data compression for the purpose of transmission (zip files)
See Wikipedia for more information: http://en.wikipedia.org/wiki/Data_compression