问题
Possible Duplicate:
Why navigator.appCodeName returning Mozilla?
When I get the PHP server variable HTTP_USER_AGENT with this code:
<?php
$useragent = $_SERVER ['HTTP_USER_AGENT'];
echo "<b>Your User Agent is</b>: " . $useragent;
?>
I get this in Google chrome:
Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4
This in firefox:
Mozilla/5.0 (Windows NT 6.1; rv:16.0) Gecko/20100101 Firefox/16.0
And this in IE:
Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0; BOIE9;NLNL)
My obvious question is how does this work. Why does my user-agent say Mozilla and Windows NT while I am using Google chrome?
Also why does it say that I use firefox when I am using IE?
回答1:
The user agent string is a text that the browsers themselves send to the webserver to identify themselves, so that websites can send different content based on the browser or based on browser compatibility.
Mozilla is a browser rendering engine (the one at the core of Firefox) and the fact that Chrome and IE contain the string Mozilla/4 or /5 identifies them as being compatible with that rendering engine.
回答2:
http://www.useragentstring.com/
Visit that page, it'll give you a good explanation of each element of your user agent.
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
来源：https://stackoverflow.com/questions/13252603/how-does-http-user-agent-work