The Internet is a worldwide network of unrelated computers that can only communicate successfully by agreeing to incorporate a set of rules or protocols. One of the most basic tenants of the Internet is the Internet Protocol (IP) address.

An IP address refers to a unique number assigned to each computer on the Internet. The IP number is called an "address" because it serves the same purpose as a home address -- it allows each machine on the Internet to be located by a numerical scheme. A domain name, such as www.findyourip.net, also maps to a numerical IP address. In this case, the IP address is 75.119.195.131.

Most people are familiar with the idea of an IP address through getting an Internet Service Provider (ISP). The ISP might offer either a dynamic or static IP address. A static IP address is a permanent address, while a dynamic address changes with each new Internet session. Every ISP has a unique range of available IP addresses.

Unless one arranges for a static IP address, a dynamic IP address is automatically assigned in the login process and will persist until the connection is intentionally ended or otherwise disabled. Upon logging in again, a new IP address is assigned. In each case, machines on the Internet will accept requests and return data to the current IP address of your machine. This IP number becomes part of the "return address" on the "envelope" as the browser requests Web pages, mail, and other online data.