An IP Address is a numeric representation of a computer's location on the Internet.
The IP in IP Address is short for Internet Protocol, and is the same term as used in the term TCP/IP, which is the universal communication method between computers on the internet.
An IP Address is actually a number between 0 and 4294967295, but to make them easier to communicate, they are often broken into four numbers, called the dotted-decimal notation.
Some examples of IP Addresses:
192.168.0.1 10.0.4.2 126.96.36.199
The dotted-decimal notation consists of four numbers, between zero and 255, and separated by three periods: "."
Each portion of the IP address has up to 256 values (zero being a possible value), meaning that the total available IP Addresses on the internet is 256 x 256 x 256 x 256 = 4294967296 computers.
Due to the fact that most Routers, Firewalls, and other network devices perform something called Network Address Translation or NAT, often a single internet address may represent more than one (even hundreds) of computers.
To convert an IP Address into a single number, the following formula can be used:
A.B.C.D IP-Integer = ((((A x 256) + B) x 256) + C) x 256) + D;
In many cases, however, this is not true. As mentioned above, a Firewall or Router performs a technical method called Network Address Translation and makes hundreds of home computers appear to all share a single, or a handful of IP Addresses.
There is a newer version of IP Addresses which supports even more unique computer addresses than the above examples.
Traditional IP Addresses in use today are called IPv4, as they can be represented by four numbers in the dotted-decimal format.
IPv6 is an extension of those addresses, and use six numbers between 0 and 255 to represent a computer address.
Using IPv6, the number of uniquely addressable computers on the internet is: 281,474,976,645,120, or 281 Trillion.
IPv6 is not in widespread use today, but has been implemented in most operating systems.