What does NAT stand for in networking?

NAT stands for Network Address Translation. It is a networking method that changes address information in packet headers so devices using one address space can communicate with devices in another.

The most familiar example is a home router. Several devices may use private IPv4 addresses inside the home, while the router translates their outgoing traffic to one public address on the internet. It tracks connections, often using port numbers, so returning traffic can be sent to the correct internal device.

NAT became important because IPv4 provides about 4.3 billion possible addresses, far fewer than the number of internet-connected devices. The technique was described as a short-term response to address depletion and routing growth, but it became widespread. NAT is sometimes mistaken for a firewall: it can make unsolicited inbound connections harder, but address translation alone is not a complete security policy.