GATEWAY

An interface that connects two different networks (a LAN can be connected to the Internet through some kind of gateway). An interface that translates between two different protocols  is also called a gateway.

A computer system that connects two incompatible services such as a commercial online service and the Internet.

The term "router" is now used in place of the original definition of "gateway". Currently, a gateway is a communications device/program which passes data between networks having similar functions but dissimilar implementations. This should not be confused with a protocol converter. By this definition, a router is a layer 3 (network layer) gateway, and a mail gateway is a layer 7 (application layer) gateway. See also: mail gateway, router, protocol converter.

Computer hardware and software that allow users to connect from one network to another.The interface between two opposing protocols.

A computer that links two networks, routing IP datagrams and often converting protocols or messages from one network to the other. The term can also refer to a system capability that provides direct access to other remote networks or services.