The information that you provide in a meta tag is used by search engines to index a page so that someone searching for the kind of information the page contains will be able to find it. The meta tag is placed near the top of the HTML in a Web page as part of the heading.
There are several kinds of meta tags, but the most important for search engine indexing are the keywords meta tag and the description meta tag. The keywords meta tag lists the words or phrases that best describe the contents of the page. The description meta tag includes a brief one- or two-sentence description of the page. Both the keywords and the description are used by search engines in adding a page to their index. Some search engines also use the description to show the searcher a summary of the page’s contents.
Although most search engines also use the contents of a page as a way to determine how to index it, the creator of a Web page should be sure to include meta tags with appropriate keywords and description. Well-written meta tags can help make the page rank higher in search results.