According to my trainer, when I'm taking ESNA class, Mr. Raj said Routers is something (software or hardware) that usually used to join or connect two or more logical subnets, which do not necessarily map one-to-one to the physical interfaces of the router. Router usually tailored to the tasks of routing and forwarding information.
Physically, Routers contain a specialized operating system such as Cisco's IOS. Router component consist of RAM, ROM, NVRAM, flash memory, and one or more processors (CPU), as well as two or more network interfaces. Router generally provides connectivity inside enterprises, between enterprises and the Internet, and inside Internet Service Providers (ISP).
Router have four different modes. The first mode is user mode, then we have privileged mode. For more deeper, we can go to global configuration mode which is used to change the configuration. The final mode is specific configuration mode.
mode 1: Router>
mode 2: Router#
mode 3: Router-config#
mode 4: Router-config-specific#
Router provides two routing types which are static routing and dynamic routing. Static routing used to reduce overhead and for security while in dynamic routing information is learned from other routers and routing protocols adjust routes automatically. Static routing does not have the scalability compared to dynamic routing. For now, these are the basic introduction about Router that I can review for the time being. Later on, for other detail information about router, I'll post it next time.