"If you maintain a portal, ecommerce site, or heavily trafficked
Web site, you might appreciate the ability to identify the
geographical location of your site visitors. Geolocation
information can help you localize content, serve relevant local
advertisements, offer a download mirror close to visitors, and
detect online fraud. Techniques like whois lookup of IP addresses
are of some help, but they don't always find accurate locations. A
better approach is a database that maps each IP address to a
location -- such as MaxMind's GeoIP.
"GeoIP is a set of databases that map IP addresses to country,
city, and Internet service provider (ISP)..."