Meta has several meanings, but generally means information about. In WordPress, meta usually refers to administrative type information. As described in Meta Tags in WordPress, meta is the HTML tag used to describe and define a web page to the outside world (search engines). In the article Post Meta Data, meta refers to information associated with each post, such as the author's name and the date posted. Meta Rules define the general protocol to follow in using the Codex. Also, many WordPress based sites offer a Meta section, usually found in the sidebar, with links to login or register at that site. Finally, Meta is a MediaWiki namespace that refers to administrative functions within Codex.