What is a gateway, and what is its role in a network topology?

"A gateway is a network device similar to a firewall, server, or router. Its function is to act as a gate between independent networks. It enables traffic to flow between networks. A gateway also protects the other nodes in a network by only allowing authorized traffic to flow between networks. All the data flows through the gateway before coming in or going out of the network. The gateway's final function is to convert data from the outside network into a protocol or a format that is compatible with the network devices in the internal network."