locate is a Unix utility first created in 1983 used to find files on filesystems. It searches through a prebuilt database of files generated by updatedb or a daemon and compressed using incremental encoding. It is significantly faster than find, but requires the database to be updated regularly. This sacrifices overall efficiency (because filesystems are regularly interrogated even when no user needs information) and absolute accuracy (since the database is not updated in real time) for significant speed improvements (particularly on very large filesystems). On fast systems with small drives, locate is neither necessary nor desirable.
The GNU version is a part of GNU Findutils.
Some versions can also be used to index network filesystems.