Default Gateway, in internet jargon, is a term for a hardware node like a router that makes it possible for devices in one network to communicate with devices in another network.
For example, when a computer needs to reach a device outside of its network or go to a web server on the internet (for example if a user goes to a webpage), it doesn’t know where to go first, because it’s outside of the local network. When this happens, the computer instead goes to the default gateway (router), which can then route the packages out from the network to the internet.
The default IP address assigned by vendors of consumer routers is often 192.168.0.1 or 192.168.1.1.