IPv4 addresses are numerical labels assigned to devices connected to a computer network that uses the Internet Protocol for communication. An IPv4 address consists of four sets of numbers, each ranging from 0 to 255, separated by periods. For example, an address might look like 192.168.1.1. This format allows for approximately 4.3 billion unique addresses. Due to the growing number of devices on the internet, the available IPv4 addresses are running out. To address this limitation, IPv6 was developed, which uses a longer address format to provide a vastly larger pool of unique addresses.