The abbreviation IPv4 stands for “Internet Protocol, version 4”. IPv4 is a data transfer protocol that appeared in 1981 and was the first widely available communication protocol on the Internet. Earlier versions were used mainly by IT professionals.
IPv4 has a 32-bit form and is written as four numbers from 0 to 255 separated by dots. For example, 64.233.191.255 or 64.18.0.0.0.
The protocol format assumes about 4.3 billion of all kinds of combinations, which was quite enough until the 80s of the twentieth century, but became insufficient later with the development of the Internet. IPv4 is gradually being replaced by IPv6 with an increased address space of 128 bits (32 characters).