User Agent String:

Explanation of what each part of the User Agent string represents.
Part	Type	Description	Version
Mozilla/5.0	Misinformation.
X11	Platform	X11 Window System	11
Linux ppc
rv:5.0.1	Rendering Engine	Geko Version	5.0.1
Gecko/20110808	Rendering Engine	Mozilla Gecko/Build Date	20110808
Firefox/5.0.1	Web Browser	Mozilla Firefox	5.0.1

A User Agent is a short string that web browsers and other applications send to identify themselves to web servers.

Unfortunately, most browsers falsify part of their User-Agent header in an attempt to be compatible with more web servers.

Click on your user-agent string (in the green box) to get a link that you can share with other people.
Visit whatsmyua.com/ua/[any-user-agent-string], the site will give you a breakdown for that string.