An IPv4 address contains 32 bits.
IPv4 represents each address as four 8-bit octets, usually written in dotted-decimal form such as 192.0.2.1. Because four octets contain 32 bits in total, IPv4 provides 2^32 possible address values, or 4,294,967,296 combinations before accounting for reserved, private, broadcast, and special-use ranges.
The limited address space became a major Internet-planning problem as more computers, phones, and connected devices came online. Network address translation helped organizations share public addresses, but it also complicated direct connectivity and some security assumptions.
IPv6 was created to provide a much larger address space. IPv6 addresses are 128 bits long, so they are not simply longer IPv4 addresses; the protocols have different notation, configuration, and operational behavior. IPv4 remains widely deployed, and many networks run IPv4 and IPv6 together during the continuing transition.