HTML meta tags are inconspicuous pieces of code that work in the background, and are typically used to provide information on the content of a Web site to search engines. Search engine optimization specialists often use meta tags to help improve the visibility of a Web site, and to help search engines better categorize and describe the Web site itself. When a Web site is submitted to a search engine, the search engine sends out a crawler or spider robot to decide whether or not the site should be indexed and, if so, how it should be categorized in the system. Meta tags help the robot decide Web site placement, how it should be described and, in some cases, how it will rank in search results.
The use of HTML meta tags was once considered an important part of search engine optimization. With the widespread abuse of meta tags, however, many search engines began to focus more on visible factors, such as written text and external linking, to help determine page ranking. HTML meta tags are now mostly used to help categorize and describe the content of a Web site, and many meta tags are discouraged from being used at all because they will often go unnoticed by search engine robots.
Although many HTML meta tags are available, only a few are widely recognized and commonly used. For example, many people use the description tag to help entice potential viewers. In some search engines, this tag will often appear in search results to help quickly describe what can be found within the website. Some search engines may use a 200 to 250 word description in its entirety, others may only show a partial description in the search results, and others still may ignore the description tag entirely and choose to create their own short description instead.
Two other commonly used HTML meta tags are the robot and keyword tags. The robot tag is recognized by most major search engines and is used to help the Web site builder specify which pages should be indexed. Keyword tags are not as widely recognized, as they are often abused. In most cases, they are best used to reinforce the importance of certain keywords that already appear in the body of a Web site. This type of tag may also be useful in helping a search engine identify variations in the spelling of certain words or phrases.