In a computer or a network, a ferret is a program that searches through selected files, databases, or search engine indexes for information that meets specified search criteria. The term derives from the name of a small furry animal, commonly a pet, that burrows under things. On the Internet, a ferret can forward a request simultaneously to a number of search engine sites and filter the results according to user-specified or program-designed guidelines.
Ferrets can be written to search a specific group of World Wide Web search engine sites, Usenet news groups, global e-mail directories, Internet Relay Channel ( IRC ) member lists, and any public, searchable database that can be efficiently selected.
A ferret should not be confused with a crawler , a program that search engines use to gather data from many Web pages that is then indexed for search retrieval.