Posted 16 May 2009 - 11:30 PM
This probably should be moved to, "Web Browsing/Email and Other Internet Applications".
To answer the question, when you go on the Internet your provider (DSL, Cable, etc.) assigns you an, "IP Address". That address is usually assigned to a city or county near you. When you go on a website they can see your IP address and look it up.
To give a brief analogy, if you gave us all your cell phone area code we can look up those numbers and see what area you live in.