search engine
Software that searches Web pages for a user-designated term and returns a list of Web pages that include the term. Search engines include a spider, also called a crawler, which combs the Web's massive network of sites by following each page's hyperlinks from site to site; a search indexer, which creates a massive catalog of all pages that have been searched; and a program that compares the user's search term against the index and returns a list of matching results. Some search engines cover virtually all possible topics, while others are focused on certain subject areas, such as technology.