html elements used to provide structured metadata about a web page. Such elements are placed in the head section of an html document.
The two most common uses of meta tags on the Web are to provide a description and to provide meta keywords for a web page. This data may then be used by search engines (such as Google) to generate and display a list of search results matching a given query.

Meta tags such as these have been the focus of a field of marketing research known as search engine optimization (SEO). In the mid to late 1990s, search engines were reliant on meta tag data to correctly classify a web page. Webmasters quickly learned the commercial significance of having the right meta tag, as it frequently led to a high ranking in the search engines - and thus, high traffic to the web site.

As search engine traffic achieved greater significance in online marketing plans, consultants were brought in who were well versed in how search engines perceive a web site. These consultants used a variety of techniques (legitimate and otherwise) to improve ranking for their clients.

In the early 2000s, search engines have veered away from reliance on meta tags since many web sites used inappropriate meta keywords or a technique known as keyword stuffing, in order to increase their search engine ranking. Many search engines, however, still take meta tags into consideration when delivering results. Currently, Google does not use meta tags to index web sites. Techniques have also been developed in order to penalize web sites considered to be "cheating the system". For example, a web site repeating the same meta keyword several times may have its ranking decreased by a search engine trying to eliminate this practice.