Switches are responsible for connecting computers within a network and it belongs only to its local network. Its responsibility is to filter and forward packets between LAN segments. They operate on layer two (2) and sometime layer three (3) of the OSI Model.
Routers on the other hand, are responsible for the interconnections of two or more networks. They forward data packets between networks. They reside at gateways, exactly where two or more networks connects. And they use communication protocols to effectively and efficiently communicate among two or more host.
A routine or subroutine, also referred to as a function procedure and sub program is code called and executed anywhere in a program. FOr example a routine may be used to save a file or display the time.
