Search Engine Terminology

What are these Meta Tags anyway?
A meta tag is a section of a web page which is invisible in a browser but readable by the search engine indexing 'spiders'. The tags contain a description of the page and a list of relevant keywords. The search engines use this information to help categorise and rank the page in their indices.

What are Keywords and Keyword Phrases?
Keywords are the words used by people looking for web site in search engines and directories. So if someone searching for a site and enters the keyword phrase "World Travel" the search engine will produce a list of sites which match these criteria.