Learn in the textbookConnecting Devices That Make Up a Network
DefinitionA router (ルーター) is a device that reads the destination IP address of each packet it receives, picks a forwarding route, and relays traffic between different networks.
ExplanationA packet (パケット), a small unit that data is split into for sending, carries the destination IP address. Choosing the path is called routing (ルーティング), and a router consults its routing table (経路表), which lists the next hop for each destination network, to decide where to send each packet. Routers sit on the border between separate networks, such as between office LANs or between a LAN and the internet.
AnalogyIt is like a guide at a fork in the road between towns who reads each parcel's address and sends it down the right road.
Memory hookA router is the thing that picks the route. Both words share the same root.