A router is a network device which connects two or more wired or wireless networks. Router keeps the networks connected to the Internet and keeps data flowing among networks. A packet of information is sent through a number of network points with routers at a known destination. Routers are located at gateways and associated with the Network layer (3) in the OSI (Open Systems Interconnection) model.
 Why is Router essential Use of Router:
~ To connect with Internet using LAN & WAN router is required.
~ To setup a VoIP (Voice over Internet Protocol) router is essential.
~ To connect multiple virtual private network (VPN) routers is essential.
 How a Router works:
Each router keeps information in a routing table about all the routers in the same or others networks (termed as neighbors) including IP address, timing, delay and others network consideration. Each packet of data arrives at router contains its source and destination IP address in terms of header information. Based on the header information the router decides which neighbor (router) it will be forwarded. Basically, it chooses the route which is least coasted and the packet is forwarded to the first router on the route.
Routers operate in two different planes-
~1. Control Plane: Here router deals with outgoing interfaces which includes forwarding packets information as well as destination address.
~2. Forwarding Plane: Which is responsible for processing of sending of a packet
 Common Types of Router:
There are several types of common use router types are as follows:
Wireless Router: It combines a number of base stations (wireless access point) as well as a number of wired LAN switch.
Modem Router: It connects more than one computer to a single DSL line for Internet access. Modem Routers provides the network address translation (NAT) which is required to support several computers, but cabling is required with an Ethernet hub or switch to actually connect them.
High-End Routers: It is a High Performance Router
Brouter: It is a network bridge combined with a router.
Edge router: This router interfaces with an ATM (Asynchronous Transfer Mode) network.