IPv4 is a 32-bit logical address used by computing devices to communicate with each other using the TCP/IP protocol stack. It is generally expressed in the decimal notation of four octets, with each octet containing 8 bits separated by a dot. The value of each octet can vary from 0 to 255. This address can further be broken down into two parts; for example, a network part and host part:

• Host part: The host part is used to identify a host on a subnet. No two hosts on the same subnet can have the same host part.
• Network part: The network part is used to identify a subnet. Hosts on the same subnet can communicate to each other without needing a router.

By using 32 bits for addresses, we can have a maximum of 4.3 billion unique addresses, many of which are reserved and cannot be used. Hence, to meet future requirements, IPv6 with an 128-bit address was created.