A computer gateway is a device or software that connects two different networks—often using different communication protocols—and enables data to flow between them by translating or converting information from one format or protocol to another. In essence, a gateway acts as a bridge and an entry/exit point for data traveling between networks or applications that otherwise could not directly communicate due to protocol differences.
Gateways convert data between different network protocols, allowing devices on separate networks (such as a local network and the internet) to communicate seamlessly. All data entering or leaving a network typically passes through the gateway, making it the main point of communication with external networks. Gateways often incorporate security functions, acting as firewalls or proxy servers to filter and control traffic, protecting the internal network from unauthorized access. They can translate addressing schemes, such as converting private local addresses to public internet addresses and vice versa.