An internet protocol (IP) address is an identifier for a computer or a device that is on a Transmission Control Protocol/Internet Protocol (TCP/IP). Networks that use the TCP/IP protocol route messages to their intended destination based on the IP address of the destination. In a sense, an IP address is analogous to the postal code on a postal address.

The format of an IP address is a 32-bit numeric address, written as four numbers separated by periods. Each number can range from 0 to 255. For example, 10.85.189.24 could be an IP address. Each number is called a class. If a network is isolated from the Internet, IP addresses can be assigned at random as long as each one is unique. But when connecting a computer to the Internet, the IP address, which can now be called an Internet address, must be...