Gateway
In plain terms
A node that bridges between two different networks.
Going deeper
A gateway is the access point connecting one network to another, often translating protocols or serving as the exit to the internet. It's the doorway out.
Under the hood
Default gateway routes traffic leaving the local network; can also translate between protocol types.
Examples
Default gateway, internet access, API gateways, protocol translation.
Think of it like...
Like the main exit door connecting your building to the outside streets.