Identifying the device requesting a response

Question

Is it possible for a web server to know which type of device request has been received from?

For example, can a create a website which shows different contents if request came from a computer (Firefox) and something different if it came from iPhone?

Answer 1

The way is the User Agent header, as has been said. You best use a list like this one to find out which mobile is it.

When I had to do something like it I stored the unknown received User Agents in a table to find out later about the ones I didn't have stored and thus wasn't able to know for sure what to serve.

Answer 2

What Mitch said, with the caveat that it's possible to falsify ones user agent.

Answer 3

Check the User-Agent in the Request Header

For full details on HTTP headers, see the specifications at http://www.w3.org/Protocols/.