The belief here is that the keywords you use in H2-H6 subheadings are more heavily weighted in Google’s algorithm than words in plain text and that tags are therefore a ranking factor of their own.

An HTML tag that identifies the contents of a Web page for the search engines. Meta tags are hidden on the page, but they, as well as all the HTML code on a page, can be viewed by selecting ...

A language that is used to define elements in a document or Web page by embedding codes (tags) surrounded by common start and stop characters. For example, the tags in SGML, HTML, XML and WML all use ...