What are meta tags?
Meta tags are HTML codes that are inserted into the header on a web page, after the title tag. They take a variety of forms and serve a variety of purposes, but in the context of search engine optimization when people refer to meta tags, they are usually referring to the meta description tag and the meta keywords tag.
The meta description tag and the meta keywords tag were proposed so that webmasters would have a consistent method for providing meta document data to user agents, such as search engines. Unfortunately, so many unscrupulous webmasters have abused the meta description and meta keywords tag that search engines have had to de-emphasize their importance. To learn more about the meta description tag, visit What are meta descriptions? To learn more about the meta keywords tag, visit What are meta keywords?
In addition to the well-known meta description and meta keywords tags, there are other useful meta tags, including the meta http-equiv tag, meta refresh tag, the meta robots tag, the meta copyright tag, and the meta author tag, among others. These tags are used to instruct user agents such as web browsers and search engine spiders on a variety of topics.
For more technical information about meta tags, visit The global structure of an HTML document – W3C Recommendation. Also see Performance, Implementation, and Design Notes – W3C Recommendation.