hub,switch and a router

To get the basic of networking one shuld know the basic difference between the three main networking devices i.e the hub,switch and a router.here is the basic difference between the three.

Hub is nothing but a very dilligent switch,it sees al computers equally.suppose there are 8 computers attached to 8 ports of a hub and if one computer sends out some data then data will be sent to all the computers attached to the hub.itdoes not read the header of the packets arriving at its input link.

switch is a bit more intelligent than a hub.it reads the header of the packets arriving at its input link
the data will be sent to the destination only which is specified in its header.the only thing which cant be done with the switch is the programming of the routing algorithm.

router is the most intelligent switch.it can be programmed likea computer.like a switch it sees the header and process it.then it finds the shortest path to the destination according to the routing algorithm fetched in it during the programming.when all these things have been done then the packet is forwarded to the destination.

basically all the threenetworking devices do one thing in common that is forwarding the packet arrived at its end .the way of forwarding is the only thing that get changed according to the devices.