A router is a device that connects two or more packet-switched networks or subnetworks, and it serves two primary functions: managing traffic between these networks and directing network data using packets that contain various kinds of data such as files, communications, and simple transmissions like web interactions). Routers can receive and send data on computer networks, and they can combine the functions of network hubs, modems, or network switches. They can also connect with devices such as hard drives and printers to improve internet access or help create business networks.

Routers use the Internet Protocol (IP) to send IP packets containing data and IP addresses of sending and destination devices located on separate local area networks. They guide and direct network data, and they can provide security by using embedded firewall and content filtering software to protect against unwanted content and malicious websites without affecting the online experience.

Routers can be physical or virtual appliances that pass information between two or more packet-switched computer networks). They can also be wireless and wired access routers that support networks to enable compute devices to connect to Wi-Fi and Ethernet LANs. Logical routers are configured partitions of traditional network hardware or physical routers that replicate the hardwares functionality, creating multiple routing domains within a single router.

In summary, a router is a networking device that forwards data packets between computer networks, and it operates at Layer 3 - the network layer - to connect networks to other networks.