What are tags?
Tags are a type of label which describes content. On this website, any content can be tagged. Each page lists the tags that have been used to describe it.
Click a tag, and the site will show you a listing of other pages (or documents, videos, etc) which use the same tag. It's a quick and simple way to find content.
You can also see a tag cloud. This is a listing of all the tags used on the site. Tags which are used a lot appear in larger text, tags which are less common appear in smaller text.