Search Engine

Search engines are tools used by computers to locate digital information. The modern search engine has evolved into a multibillion dollar advertising machine that keeps track of user search data and sites visited. Search engines have also become a primary tool for nonprofit organizations, businesses, marketers, and advertisers to attract customers online.

Modern search engines are capable of searching for images, texts, video, maps, news, scholarly articles, patent filings, entertainment, and more. Search engines can conduct sophisticated textual searches using Boolean logic, image searches by timeframe, size, similarity of content, color, theme, faces, image type, for example, and can conduct sophisticated data and information searches.

Although the term search engine is most closely associated with the tools used to search for information on the World Wide Web, any digital search interface such as http://eBay.com or http://Amazon.com, or the interfaces used by universities and public libraries to search for books, magazines, multimedia documents, and so forth can be called search engines. Search engines work by examining archival databases generated from the billions of currently accessible websites.

Search engines use an assortment of indexing logics. Most search engines create indexes based on keywords, phrases, categories, and other heuristics. Some search engines like Yahoo, use human beings to help create categories and index data, while other sites like Google do all of their indexing electronically, via spiders and robots (programs that automatically examine webpages and create keyword and phrase indexes).

Initially, scores of search engines competed for success. Only a handful of search sites have survived as key players. Google and Yahoo have emerged as two of the most visited and most used websites in the world.