There are several ways of identifying a browser, but by using below JavaScript code you can Indentify Each and everything about browser.See the below example:
<html>
<body>
<script type="text/javascript">
var x =
navigator
document.write("CodeName="
+ x.appCodeName)
document.write("<br>")
document.write("MinorVersion="
+ x.appMinorVersion)
document.write("<br>")
document.write("Name="
+ x.appName)
document.write("<br>")
document.write("Version="
+ x.appVersion)
document.write("<br>")
document.write("CookieEnabled="
+ x.cookieEnabled)
document.write("<br>")
document.write("CPUClass="
+ x.cpuClass)
document.write("<br>")
document.write("OnLine="
+ x.onLine)
document.write("<br>")
document.write("Platform="
+ x.platform)
document.write("<br>")
document.write("UA="
+ x.userAgent)
document.write("<br>")
document.write("BrowserLanguage="
+ x.browserLanguage)
document.write("<br>")
document.write("SystemLanguage="
+ x.systemLanguage)
document.write("<br>")
document.write("UserLanguage="
+ x.userLanguage)
</script>
</body>
</html>