What is an IP address?
An identifier for a computer or device on a TCP/IP network. Networks using the TCP/IP protocol route messages based on the IP address of the destination.(Webopedia)
Every machine on the Internet has a unique identifying number, called an IP Address. A typical IP address looks like this:
221.24.60.157
If you are using cable as your Internet connection, you could have a permanent IP address, (also know as Static), or you could have an address that changes every few months. Not all cable companies offer a permanent address.
If you are using dialup as your Internet connection, then your IP address is different everytime you connect.
From a hackers point of view, he is looking for your IP address, to try to get into your computer.
A personal firewall can help to keep any hackers out. Windows XP has one built in, go to "Network Connections" in your control panel. Right click on "Local area connection", then click the "Advanced" tab. Keep in mind if you use a firewall, there may be some web sites that you can not get into. If this happens, you will have to disable the firewall to get to the web site, then reactivate it after you leave. There are free firewalls available also, here is one. Check out Zone Alarm
If you are interested in seeing what your IP address is, click here
IP Address