IP refers to the Internet Protocol, the primary communications protocol within the Internet protocol suite for the transmission of datagrams over the boundaries of networks, and it’s routing functionality is integral to the operation of the Internet.
As the principal protocol in the Internet layer of the Internet protocol suite, IP is tasked with delivering packets from the a source host to a destination host entirely based on the IP addresses contained in the packet headers, defining the packet structures which encapsulate the data being transmitted. IP also designates the addressing methods which are used to label datagrams with information regarding their destination and source.
As its name implies, IP addressing involves the assigning of IP addresses and related parameters to host interfaces. IP routing is performed by all manner of hosts, but crucially by routers, which transport packets between networks. Routers interact with each other using either interior gateway protocols or exterior gateway protocols, depending on the nature of the network’s architecture.
Currently, the fourth version of IP (IPv4) is still dominant on the Internet, but its successor protocol, IPv6, began being deployed commercially in 2006, and is gradually being used more widely. IPv6 was developed in anticipation of IPv4 address exhaustion; IPv4 uses a 32-bit address, while IPv6 uses 128-bit.