To explain the concept of a router, we must first introduce what routing is. "Routing" refers to the act of transmitting data from one place to another. A router is the machine that performs this action, with its English name being "Router." It is a network layer device that uses one or more metric factors to determine the best path for network communication. Routers forward packets from one network to another based on network layer information. Occasionally, they are also referred to as gateways (although this definition of gateways is now outdated).
Routers are one of the essential network devices in interconnected networks. A router is a network device that connects multiple networks or network segments. It can "translate" data information between different networks or segments so that they can "read" each other's data, thereby forming a larger network. Routers have two major typical functions: data channel functions and control functions. Data channel functions include forwarding decisions, backplane forwarding, and output link scheduling, which are usually completed by specific hardware. Control functions are generally implemented through software and include information exchange with adjacent routers, system configuration, and system management.