How do I detect what browser (IE, Firefox, Opera) the user is accessing my site with? Examples in Javascript, PHP, ASP, Python, JSP, and any others you can think of would b
check out browsecap.ini. The linked site has files for multiple scripting languages. The browsecap not only identifies the user-agent but also has info about the browser's CSS support, JS support, OS, if its a mobile browser etc.
cruise over to this page to see an example of what info the browsecap.ini can tell you about your current browser.