A technique that shrinks program or data files so that they occupy less disk space. The file must then be extracted or decompressed before use. Some types of files, such as word processor documents, can be compressed by 50 percent or more. Recompressing an already compressed file usually makes the file slightly larger because of the compression overhead.
File compression can be automatic and performed by the operating system, or it can be manual and performed by a file-compression program.
See also file-compression program.