WhichBrowser
Browser sniffing gone too far — A useragent parser library for PHP
... to know which score belongs to which browser. To do that you need a browser sniffing library. Almost all browsers say they are Netscape 5 and almost all WebKit browsers say they are based on Gecko. Even Internet Explorer 11 now no longer claims to be IE at all, but instead, an unnamed browser that is like Gecko. And it gets worse. That is why it is complicated.