Editing IP address (section)

==IP versions==
Two [[Internet Protocol#Version history|versions of the Internet Protocol]] are in common use on the Internet today. The original version of the Internet Protocol that was first deployed in 1983 in the [[ARPANET]], the predecessor of the Internet, is [[Internet Protocol version 4]] (IPv4).

By the early 1990s, the rapid [[IPv4 address exhaustion|exhaustion of IPv4 address space]] available for assignment to [[Internet service providers]] and end-user organizations prompted the [[Internet Engineering Task Force]] (IETF) to explore new technologies to expand addressing capability on the Internet. The result was a redesign of the Internet Protocol which became eventually known as [[Internet Protocol Version 6]] (IPv6) in 1995.<ref name=rfc1883/><ref name=rfc2460/><ref name=rfc8200/>
IPv6 technology was in various testing stages until the mid-2000s when commercial production deployment commenced.

Today, these two versions of the Internet Protocol are in simultaneous use. Among other technical changes, each version defines the format of addresses differently.  Because of the historical prevalence of IPv4, the generic term ''IP address'' typically still refers to the addresses defined by IPv4. The gap in version sequence between IPv4 and IPv6 resulted from the assignment of version 5 to the experimental [[Internet Stream Protocol]] in 1979, which however was never referred to as IPv5.

Other versions v1 to v9 were defined, but only v4 and v6 ever gained widespread use. v1 and v2 were names for [[TCP protocols]] in 1974 and 1977, as there was no separate IP specification at the time. v3 was defined in 1978, and v3.1 is the first version where TCP is separated from IP. v6 is a synthesis of several suggested versions, v6 ''Simple Internet Protocol'', v7 ''TP/IX: The Next Internet'', v8 ''PIP — The P Internet Protocol'', and v9 ''TUBA — Tcp & Udp with Big Addresses''.<ref name="delong2017">{{Cite web |last=DeLong |first=Owen |title=Why does IP have versions? Why do I care? |url=https://www.socallinuxexpo.org/sites/default/files/presentations/Why%20IP%20Versions%20and%20Why%20do%20I%20care.pdf |access-date=24 January 2020 |website=Scale15x}}</ref>