An Net Protocol (IP) address is a numerical label that is assigned to devices participating in a computer network that uses the Net Protocol for communication between its nodes.[1] An IP address serves four principal functions: host or network interface identification & location addressing. Its role has been characterized as follows: "A name indicates what they seek. An address indicates where it is. A route indicates how to get there."[2]
The designers of TCP/IP defined an IP address as a 32-bit number[1] & this process, known as Net Protocol Version 4 or IPv4, is still in use today. However, due to the giant growth of the Net & the resulting depletion of available addresses, a new addressing process (IPv6), using 128 bits for the address, was developed in 1995[3] & last standardized by RFC 2460 in 1998.[4] Although IP addresses are stored as binary numbers, they are usually displayed in human-readable notations, such as 208.77.188.166 (for IPv4), & 2001:db8:0:1234:0:567:1:1 (for IPv6).
The Net Protocol also routes information packets between networks; IP addresses specify the locations of the source & location nodes in the topology of the routing process. For this purpose, a quantity of the bits in an IP address are used to designate a subnetwork. The number of these bits is indicated in CIDR notation, appended to the IP address; e.g., 208.77.188.166/24.
As the development of private networks raised the threat of IPv4 address exhaustion, RFC 1918 set aside a group of private address spaces that may be used by somebody on private networks. They are often used with network address translators to connect to the global public Net.
The Net Assigned Numbers Authority (IANA), which manages the IP address space allocations globally, cooperates with four Regional Net Registries (RIRs) to allocate IP address blocks to Local Net Registries (Net service providers) & other entities.