An Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing.
Internet Protocol version 4 (IPv4) defines an IP address as a 32-bit number. However, because of the growth of the Internet and the depletion of available IPv4 addresses, a new version of IP (IPv6), using 128 bits for the IP address, was developed in 1995,and standardized in December 1998. In July 2017, a final definition of the protocol was published. IPv6 deployment has been ongoing since the mid-2000s.
An IPv4 address has a size of 32 bits, which limits the address space to (232) addresses. IPv4 addresses are usually represented in dot-decimal notation, consisting of four decimal numbers, each ranging from 0 to 255, separated by dots, e.g., 10.10.10.0. Each part represents a group of 8 bits (an octet) of the address. In some cases of technical writing, IPv4 addresses may be presented in various hexadecimal, octal, or binary representations.
IPv6, the address size was increased from 32 bits in IPv4 to 128 bits or 16 octets, thus providing up to 2128 addresses. This is deemed sufficient for the foreseeable future. The large number of IPv6 addresses allows large blocks to be assigned for specific purposes and, where appropriate, to be aggregated for efficient routing. With a large address space, there is no need to have complex address conservation methods as used in CIDR.