User Agent String explained :
|  Firefox 21.0 | |
|---|---|
| Mozilla | MozillaProductSlice. Claims to be a Mozilla based user agent, which is only true for Gecko browsers like Firefox and Netscape. For all other user agents it means 'Mozilla-compatible'. In modern browsers, this is only used for historical reasons. It has no real meaning anymore | 
| 5.0 | Mozilla version | 
| Windows NT 5.1 | Operating System:  Windows XP | 
| rv:21.0 | CVS Branch Tag The version of Gecko being used in the browser | 
| Gecko | Gecko engine inside | 
| 20130331 | Build Date: the date the browser was built | 
| Firefox | Name :  Firefox | 
| 21.0 | Firefox version | 
| First visit: | 2013.04.01 10:37 | 
| Last visit: | 2022.09.08 03:48 | 
| All Firefox user agent strings | |