A host, in this context, is any computer connected to the network. A wide variety of networks reside on the Internet, often using different hardware and running different software. Gateways and bridges enable these different networks to communicate with each other. A gateway has a broader range than a bridge. It operates above the link layer and translates, when required, the interface and protocol used by one network into those used by another distinct network.
Gateways allow data transfers across the various networks that constitute the Internet.
Routing Using domain names for addressing and gateways for translation greatly facilitates the routing of the data being transferred. Routing is the assignment of a path by which a message reaches its destination. The domain name effectively defines the message destination. In a large network like the Internet, information is routed from one communications network to the next until that information reaches its destination. Each communications network checks the domain name and, based on the domains with which that network is familiar, then routes the information on to the next logical stop.