In general, meta information (or meta data) refers to information about information. For example, the table of contents and index of a book are meta information about the actual information the book contains. HTML provides the meta element, used in the head section, to provide information about the actual information in the Web page.

Search engines use automated programs that go around the Web following every link they find to create the large databases of Web sites. These automated programs are called by several names: Spiders, Crawlers, WebBots. Crawlers use a Web page's meta information as a main source of information about the nature of a page it finds.

The meta keywords help tell search engines which searches should match the page. The meta description may actually be shown verbatim in the search engine results page. There are many other uses for meta elements, with various attributes and values as listed in the W3Schools Meta Element Summary.