User Agent String:

Explanation of what each part of the User Agent string represents.
Part	Type	Description	Version
Mozilla/5.0	Misinformation.
Windows NT 6.1	Operating System	Windows 7	6.1
AppleWebKit/537.1	Rendering Engine	WebKit Rendering Engine	537.1
KHTML, like Gecko	Misinformation.	Apple WebKit is based on KDE KHTML
Chrome/21.0.1180.60	Web Browser	Google Chrome Browser	21.0.1180.60
Safari/537.1 AlexaToolbar/alxg-3.1	Misinformation.

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.