NAT
NAT (Network Address Translation) is the mechanism a router uses to let every device on a private network -- laptops, phones, smart TVs -- share a single public IP address when talking to the internet. The router keeps a translation table mapping each internal device's private address and port to a public port, rewriting packets in both directions so replies reach the right device. Without NAT, every device would need its own public IPv4 address, which the internet ran out of long ago. Home routers do one layer of NAT; some ISPs add a second layer on top, called CGNAT, which shares one public address across multiple customers' routers rather than just one household's devices.
By AdminKit team, Netbase JSC · Updated