What is Network Router
Routers are hardware equipment which is used for connecting many wired/wireless networks to each other. It is a layer 3 gateway; hence it works at the network level of the OSI model.
Home networks often use IP routers (which can be wired or wireless), this is because IP is the most popular OSI network level protocol. Thus DSL or cable modem broadband routers are used to connect the LAN to the internet WAN.
Routers are capable of filtering traffic (both ingoing and outgoing) by keeping track of the IP addresses of the computers, they manage this through the routing table where the configuration settings are kept (the routing table can be updated through the browser on some routers).
Broadband routers are quite adept these days as they integrate the functions of routers, switches and firewalls in one piece of hardware.