Large files use a lot of disk space and take longer than smaller files to transfer from one system to another over a network. If you do not need to look at the contents of a large file very often, you may want to save it on a magnetic tape, CD-ROM, or other medium and remove it from the hard disk. If you have a continuing need for the file, retrieving a copy from a tape may be inconvenient. To reduce the amount of disk space you use without removing the file entirely, you can compress the file without losing any of the information.
You frequently get a compressed file when you download files from the Internet. The utilities described following compress and decompress files by using various tools.