I can think of a number of things something with such a name could be useful for but this is actually for giving you access to edit web pages that have a format of a wiki or similar. These pages are increasing in popularity, especially as the technology has now got round or over many of the barriers that prevented people using them. Now, in many cases, like PBwiki for example, it really is just a matter of clicking and typing or adding an image or link.
The Universal Edit Button will allow you to do just that, where you have access, of course. Eventually this will be a standard feature of any browser but until then download the Button from this link to get the Firefox extension. Some say it works in IE but I have no idea how.