IPv4 (Internet Protocol version 4) is the most widely used protocol for internet communication. It uses a 32-bit address format, allowing for approximately 4.3 billion unique addresses. For example, a typical IPv4 address looks like "192.168.0.1".
IPv6 (Internet Protocol version 6) is the successor to IPv4, designed to address its limitations, such as the shortage of addresses. It uses a 128-bit address format, allowing for a vastly larger number of unique addresses. An example of an IPv6 address is "2001:0db8:85a3:0000:0000:8a2e:0370:7334".