The IP address is a 32 bit (4 byte) binary number that uniquely identifies a host on the Internet. IP addresses are normally written in dotted quad notation where each byte of the four byte address is written as a base-ten number in the range 0-255.

As an example, Swansea University's web server has IP address 10001001 0101100 00000001 00000111 which is much more memorable when written as 137.44.1.7.

The IP addressing scheme is designed to allow the grouping of geographically close hosts into sub networks which can be arranged in a hierarchy so to facilitate management of the address range and to allow efficient routing. The most-significant bits of a given IP address identify a network that a given host belongs to. The fewer bits used for this network address, the higher the network is in the global hierarchy of Internet Service Providers (ISPs). The remaining bits give the address of a given host within the network. Another binary number, called a bitmask is used to separate the host address from the network address and is used to make forwarding decisions when routing datagrams between networks.

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