A gateway can refer to a couple terms:
A gateway is a node in a computer network that serves as an entrance to another network. A node is a processing location where data stops for either transporting or reading. For example, a computer or modem is a node, whereas a computer cable isn’t. A gateway is a stopping point for data on its way to or from other networks. Because of gateways, sending data back and forth is possible.
A gateway node can run application services and perform computations. It is the entry point to the domain.
In the workplace, the gateway is the computer that routes traffic from a workstation to the outside network that serves the web pages. The gateway node operates as a firewall and proxy server. The firewall keeps out unwanted traffic. The proxy server makes sure the real server can handle online data requests. For home use, the gateway is the Internet Service Provider (ISP) that connects the user to the internet.
The term gateway is sometimes used interchangeably with router, but they are not the same. A router is a physical device that connects a modem to all of the network-connected devices such as computers, smartphones, and home cameras. A gateway is different in that it is simply a combination of a router and modem. It combines the two to provide one single piece of hardware.
A satellite gateway is a computer system located on a ground station on Earth that transmits data and voice signals to and from the satellite in orbit to the local area network. It houses the antennas and equipment that convert Radio Frequency signal to an Internet Protocol signal for terrestrial connectivity.