The title is pretty clear.
My website consists of both English-written and Spanish-written versions. You can go to the main site, which is in Spanish, by clicking http://www.chrishonn.com and to the translated version, which is in English, at http://en.chrishonn.com. At the index of each page, there is a link (at the bottom) that allows the user to pass from one site to the other.
However, I was wondering, how big sites like Google, Yahoo!, and other brands' websites recognize the user's geographical location/IP so that - depending on that - the site's language is adapted (i.e. you are from China and you visit www.google.com, you'll be redirected to www.google.cn).
I have stated on every single page of my website the language:
<meta http-equiv="content-language" content="en">
That example is of course from one of the http://en.chrishonn.com sites, which are in English.
I hope someone can give me a hand. Thank you (if I missed something, please let me know).