Every computer that has ever been connected to the Internet has been given an Internet Protocol (IP) address. This IP address is used as a type of location tool, which allows a network administrator or Internet service provider to differentiate one computer from another. While an IP address won't be able to tell you exactly where someone lives, it will be able to confirm the general area in which they reside--sometimes within a couple of blocks of their actual location.
Use the IP address look-up feature at WhatismyIPaddress.com (see References). This site will tell you exactly what your IP address is and let you search for people using their IP addresses. Type an IP address into the box on screen and click "Lookup IP Address" to find relevant information about that IP address's physical location.
Use the Whois lookup function of cqcounter.com's IP address search engine (see References). Type the IP address that you're researching into the box on screen. Click the "Whois" button to perform your search, which will give you information such as the Internet service provider the IP address owner uses and approximately where they live.
Search using IPAddressLocation.org (see References). Type the IP address in question into the box on the IP Address Location homepage. Click the radio button next to the "ipaddresslocation.org" and then click on the "Search" button to view the results page for the IP address you provided. You will then be given a variety of tidbits of information about the person who is associated with that IP address, including their approximate location.