NAT
In plain terms
Translating private network addresses to a public one.
Going deeper
Network Address Translation lets many devices on a private network share a single public IP by rewriting address info in packets. It conserves scarce public IPs.
Under the hood
Eased IPv4 exhaustion and adds a layer of isolation; complicates inbound connections and peer-to-peer.
Examples
Home routers, IPv4 conservation, private networks, port forwarding.
Think of it like...
Like an office switchboard where many internal extensions share one public phone number.