If you for whatever reason need to find someone and all you have is an IP address, there aren't numerous options, but there are a few you can take.

If you don't know what an IP address is, it . Your computer is given one every time you connect to the Internet so other computers can identify it.

As one would expect, there are online search tools for this purpose, including Abika. This search tool allows one to discover the location of the address as well as the name and address of the owner. Just remember that the owner of the address isn't always the user; someone else can use the computer easily, perhaps without the permission of the owner. The tool also allows one to do a reverse search on a variety of e-mail addresses (forwarding and more), instant messenger screen names, discover the addresses of those who make blog posts, and search for websites by the IP address. IP Address Location is another option.

Someone may want to perform such searches to discover the origins of criminal activity, such as stolen social security numbers. Any sort of online fraud may potentially be revealed with the ability to identify IP addresses.

So there are searches such as these, but the chances are that it will be very difficult to locate a specific person using an IP address alone. Most of the time, looking for someone based only on that information means one will be able to determine the network or general location.

However, once someone can determine that information, it is possible to track activity from that area and piece together the identity of the owner and even the user.

For more information about this, read Peter Fleischer's blog: Privacy...?: Can a website identify a user based on IP address?