Print this article for free. Along with the Document object, each browser window has a Navigator object, which has two properties containing all the information about the sort of browser you're using. These are appName and appVersion . The application name is appName . So, if you just want to know whether someone's using Netscape or MSIE, use appName .
More information is stored in the appVersion .
Beyond the version number, you probably won't need all that information. Different browsers do all kinds of different and possibly weird things in the string, and the only thing you can count on is that the first item listed will be the version number. The way to tell which browser is used differs between browsers. Ah, life on the Web. OK, let's do something useful with this information.