Technically speaking, a gateway is an entry mode from one network to another. In the terms of telecommunications, the gateway is the point that connects the networks. It is a key feature of most routers and devices that can accept transfer and relay information packets across networks that use similar protocols. However, it can accept information from one type of protocol and convert it into another protocol that is of a different format.
Generally, a gateway can be implemented in both hardware and software or both, but in most cases they are implemented by software installed within the system.
The gateway may contain a large number of devices that may be needed to achieve system interoperability. There must also be the presence of administrative procedures that are acceptable to both types of networks. A gateway for protocol mapping or translation can be used for interconnecting networks with different protocol technologies effortlessly.