A gateway is a piece of hardware that allows the secure transmission of data from one network to another. It acts as a ‘stopping point’, as it controls the flow and traffic in and of out of networks. A proxy server is an example of a gateway, because it sits between a client and another server.
Another function of a gateway is to connect networks with different protocols, or set of rules, together. For instance, WiFi uses a particular network protocol while machines that connect to the internet utilize Internet Protocol (IP) and a handful of other related protocols: A gateway helps the transfer of information between the two protocols to provide the connected user with a seamless experience.