An Internet Protocol address (IP address) is a usually numerical label assigned to each device (e.g., computer, printer) participating in 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. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."
The designers of the Internet Protocol defined an IP address as a 32-bit number
and this system, known as Internet Protocol Version 4 (IPv4), is still in use today. However, due to the enormous growth of the Internet and the predicted depletion of available addresses, a new addressing system (IPv6), using 128 bits for the address, was developed in 1995,
standardized as RFC 2460 in 1998, 
and is being deployed worldwide since the mid-2000s.
IP addresses are binary numbers, but they are usually stored in text files and displayed in human-readable notations, such as 172.16.254.1 (for IPv4), and 2001:db8:0:1234:0:567:8:1 (for IPv6).
The Internet Assigned Numbers Authority (IANA) manages the IP address space allocations globally and delegates five regional Internet registries (RIRs) to allocate IP address blocks to local Internet registries (Internet service providers) and other entities.
 RFC 760, DOD Standard Internet Protocol (January 1980)
 RFC 791, Internet Protocol - DARPA Internet Program Protocol Specification (September 1981)
 RFC 1883, Internet Protocol, Version 6 (IPv6) Specification, S. Deering, R. Hinden (December 1995)
 RFC 2460, Internet Protocol, Version 6 (IPv6) Specification, padnda'srockS. Deering, R. Hinden, The Internet Society (December 1998)