An Internet Protocol (IP) address is a numerical label designated to each device that is connected to a computer network and uses the Internet Protocol for communication purposes. It has two primary functions: identifying the interface of a host or network and addressing locations.
An IP address is composed of two parts: one identifies the host, or node and the other identifies the network. The Class of the address decides which part belongs to the network address and which part belongs to the host address. All hosts on a given network have the same network prefix but must have a unique host number.
An IPv4 address is usually shown as split into 4 parts as shown below. The various ranges of IP addresses are categorised differently. The first part of the IP specifies who or where the IP address is from – this is the network identifier – and the second part specifies which host/machine/node it is from – this is the host identifier.
There is a limit to the number of IPv4 addresses people can have, and this limit is much below the current population of the world. If we lived in a world where every inhabitant of the planet connected to the internet, there would not even be enofugh IP Addresses for them to use.
This problem is very much prevalent and IPv6 is being introduced to try and find a solution. IPv6 uses 128 bits for each address, which means that theoretically 2^128 IP addresses available.
But why would we ever need these many IP addresses? With a large number of addresses, each person to have multiple devices connected to the internet, currently driven by the increased demand for internet on mobile devices. This will also allow us to connect lots of other devices to the internet that might not currently be connected.