Meta-tag

In HTML and XHTML documents, meta elements are tags that give structured metadata about a Web page. They are a component of the header of a web page. On the same page, several Meta elements with various properties may be used. The page description, keywords, and any other metadata not already supplied by the other head elements and attributes can be specified using meta elements.

The meta element can be used to provide additional metadata to an HTML document or to mimic the use of an HTTP response header field.

Meta element used in search engine optimization:

They have been the subject of research in the area of marketing called search engine optimization (SEO), where various techniques are employed to give a user's website a higher rating on search engines. Prior to the mid-1990s development of content analysis by search engines (most notably Google), webmasters soon realised the need of providing the appropriate meta elements since search engines relied on metadata to accurately identify a Web page. The importance of meta tags is now a contentious issue among search engine users. Many just come to the conclusion that there is no definitive answer but because they don't hurt, they use them just in case. Some say they are irrelevant, others say they are essential.