IPv4

IPv4 is the fourth version of the Internet Protocol, routing packets across interconnected networks with 32-bit addresses. Its finite address space supports about 4.3 billion unique addresses.

IPv4 packet: A formatted unit of IPv4 data containing a header and payload. Its header carries the addressing and control information routers use to forward each datagram.
Internet Protocol: The network-layer protocol family that carries datagrams between hosts across interconnected networks. IPv4 is one version of this protocol, alongside IPv6.
IPv6: The sixth version of the Internet Protocol, using 128-bit addresses and a redesigned packet format. IPv6 expands address capacity and changes packet handling rather than extending IPv4's 32-bit format.
Internet Protocol Suite: The layered set of protocols used to communicate across the Internet. IPv4 emerged as the network-layer component of this interoperable protocol suite.
IPv4 address exhaustion: The depletion of unallocated public IPv4 address blocks available for distribution. The finite 32-bit address pool made scarcity a defining pressure on IPv4 deployment.
IPv4 addressing: The scheme for assigning and interpreting 32-bit IPv4 addresses. Address structure determines which destination networks routers can recognize.
IP address: A numerical identifier assigned to an interface for communication using the Internet Protocol. An IPv4 address is a 32-bit member of this broader addressing concept.
Network address translation: A technique that modifies IP address information as packets cross a network boundary. NAT conserves public IPv4 addresses, but complicates direct end-to-end communication.
Vint Cerf: An American computer scientist who helped develop the TCP/IP protocols. Cerf helped shape the internetworking architecture in which IPv4 operates.
Regional Internet registry: An organization that allocates and registers Internet number resources within a geographic region. Registries distribute IPv4 address blocks and manage increasingly scarce allocations.

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Network packetBroader topic: IPv4 defines a widely deployed packet format and its header fields.