A search engine is a website that allows users to look up information on the World Wide Web (WWW), known as the Internet. The search engine will achieve this by looking at many web pages to find matches to the user's search inputs. It will return results ranked by relevancy and popularity by the search engine. Some popular search-engines are Google, Yahoo!, Ask.com, Forestle and Bing. Older services include Webcrawler, Lycos, and Alta Vista.