IP v 4 (IP4) and IP v 6 (IP6) are two IP address protocols. IPv4 was envisioned before the proliferation of internet connected devices and supports up to roughly 4.3 billion IP addresses. Although this might sound like a lot, it's not nearly enough given that the IP address system is used around the world. IPv6, the later version of the protocol, solves this issue and has a capacity of up to 340 undecillion ip addresses (a very very high number!).