Header Info

[PHPGuru2]

Is it possible to determine where user is coming from or located geographically?

For example, let's say that you would like to let users from US only view certain contents of your website, can you do it from information in request header? (user IP or something else)

Another question, are IP addresses different from country to country?
or do they share the same part in their IPs?

[ScubaKing22]

Well IP is a standard protocol, but there could be a pattern of some sort in different countries. As for determining a user's location, I searched google and couldn't find anything helpful, but I think there is a website I've seen that can do that, although it was a few years ago if that's indeed what I'm thinking of.