User Agent String.Com 

User Agent String explained :

Opera 9.70
Mozilla	It's a Mozilla based browser
5.0	Mozilla Version
Linux i686	Operating System: Linux running on a Intel Pentium Pro CPU
U	Security values: N for no security U for strong security I for weak security
en	Language Tag, indicates the language for which the client had been localized (e.g. menus and buttons in the user interface) en = English
rv:1.8.1	CVS Branch Tag The version of Gecko being used in the browser
Gecko	Gecko engine inside
20061208	Build Date: the date the browser was built
Firefox	Opera pretends to be Firefox
2.0.0	Version
Opera	Name : Opera
9.70	Browser version
First visit:	2009.03.09 04:12
Last visit:	2009.10.06 05:08
All Opera user agent strings