Two versions of the Internet Protocol (IP) are in use: IP Version 4 and IP Version 6.

IPv4 addresses are usually represented in dot-decimal notation (four numbers, each ranging from 0 to 255, separated by dots, e.g. 208.77.188.166). Each part represents 8 bits of the address, and is therefore called an octet. In less common cases of technical writing, IPv4 addresses may be presented in hexadecimal, octal, or binary representations. In most representations each octet is converted individually.
Source: Wikipedia