A program that searches documents for specified keywords and returns a file list of corresponding matches. Although search engine is really a general class of programs, the term is often used to designate specific systems that enable users to search for documents on the World Wide Web and USENET newsgroups; including: All The Web, Alta Vista, Archie, Excite, Google, HotBot, InfoSeek, Jughead, Lycos, Veronica, WebCrawler, Yahoo!. Search engines typically work by sending out a spider (qv) to fetch as many documents as possible. Another program, called an indexer, then reads these documents and creates an index based on the words contained in each document. Each search engine uses a proprietary algorithm to create its indices such that, ideally, only meaningful results are returned for each query. Also called "webot" (contraction of web and robot) for obeying instructions to automatically retrieve internet data. See crawler, spider, meta tag, portal, program, software.