PAT
termnetworking
Stands for: Port Address Translation
Translating many private addresses onto one public address by also rewriting ports - what most people mean when they say NAT.
The port is what makes the sharing possible: the translating device keeps a table mapping each internal conversation to a unique source port on the shared address, and reverses it on the way back. Two consequences follow directly. The table is finite, so a host opening thousands of connections can exhaust it for everyone behind the same address. And attribution collapses - an address in a log identifies the gateway, not the user, which is the problem carrier-scale deployments create everywhere they are used.
Also known as: Port Address Translation, overload