/ˌaɪ-ˌpiː-viː-ˈfɔːr/
n. “The original numbering system of the internet.”
IPv4, short for Internet Protocol version 4, is the fourth version of the Internet Protocol and the foundational addressing system that made the modern internet possible. It defines how devices are identified and how data packets are routed across networks so they arrive at the correct destination.
An IPv4 address is a 32-bit number, typically written in dotted-decimal notation, where the address is split into four 8-bit segments (octets) separated by dots. Each octet ranges from 0 to 255.
A common example of an IPv4 address looks like this:
192.168.1.1Key characteristics of IPv4 include:
- 32-bit Address Space: Provides approximately 4.3 billion unique addresses.
- Hierarchical Structure: Addresses are divided into network and host portions to enable routing.
- Widespread Adoption: Still heavily used across the internet despite address exhaustion.
- Supports NAT: Technologies like PAT and NAT extend IPv4 usability by allowing many devices to share a single public IP.
Over time, the explosive growth of internet-connected devices led to IPv4 address exhaustion, meaning most publicly routable IPv4 addresses have already been allocated. This limitation is one of the main reasons for the development of IPv6, which dramatically expands the available address space.
Conceptually, IPv4 functions like a global postal system for the internet — every device gets an address, routers read that address, and packets are forwarded hop-by-hop until they reach the correct destination.
In essence, IPv4 is the original backbone of internet addressing: simple, elegant, and still essential, even as the network evolves beyond its original limits.