Example: "Most computers display their IP address in the IPv4 format."
IPv4 is the fourth revision of the Internet Protocol and is the most common version used today. It uses 32-bit addresses, which are formatted as "220.127.116.11." Each section may contain a number from 0 to 255, which provides a total of 4,294,967,296 (2^32) possible addresses.
Since each computer connected to the Internet must have a unique IP address, 4.3 billion IP addresses is not enough to cover the worldwide requirement for unique IPs (nice planning guys). Therefore, IPv6, which supports 128-bit IP addresses, is currently being developed to replace IPv4.
Updated: May 18, 2009