---
title: IPv4
slug: Glossary/IPv4
tags:
  - Glossary
  - IPv4
  - Infrastructure
  - Internet Protocol
  - Protocol
---
IPv4 is the fourth version of the communication {{Glossary("protocol")}} underlying the {{glossary("Internet")}} and the first version to be widely deployed.

First formalized in 1981, IPv4 traces its roots to the initial development work for ARPAnet. IPv4 is a connectionless protocol to be used on packet-switched Link layer networks (ethernet). {{glossary("IPv6")}} is gradually replacing IPv4 owing to IPv4's security problems and the limitations of its address field. (Version number 5 was assigned in 1979 to the experimental Internet Stream Protocol, which however has never been called IPv5.)

## See also

{{interwiki("wikipedia", "IPv4", "IPv4")}} on Wikipedia
