A user agent is a text sequence that a browser reports to a web site containing information such as the brand, version, plugins, and toolbars installed on the browser. This information helps web sites determine what capabilities a browser has, and helps the web site provide pages that cater to the browser.
In addition, robots, spiders, or "bots" that surf the web report a user agent to web sites. Bots are automated software that surf web sites looking for information. Popular bots include the Googlebot, MSNBot, and Yahoo! Slurp. These bots crawl the web to find content to include in their search engines.
By checking the user agent of your browser's http request, this site can see the user agent your browser is reporting. The browser you are surfing with is reporting this user agent text:
Mozilla/5.0 (Windows; U; Windows NT 5.1; id; rv:1.9.2.8) Gecko/20100722 Firefox/3.6.8
Each web site that reads user agent information must do this by checking the text sent in an HTTP request for a web page. This text is retrieved differently depending on the type of web site that is being surfed. For example, ASP web sites check for user agent text by checking the Request.ServerVariables collection for the "HTTP_USER_AGENT" element.
iPhone
Android
iPod
mobile
Blackberry
script
motorola
google earth
spyware
psycheclone
iTunes
