Routers connect two or more logical subnets, which do not necessarily map one-to-one to the physical interfaces of the router. The term “layer 3 switch” often is used interchangeably with router, but switch is a general term without a rigorous technical definition. In marketing usage, it is generally optimized for Ethernet LAN interfaces and may not have other physical interface types. In comparison a network hub does not do any routing, instead every packet it receives on one network line gets forwarded to the other network lines.
Cisco is the world largest supplier of network routers as well as the most known.