[Ilugc] [OT] doubt on Networking on linux

[peevee]

hi luggies,
i want to know what the basic use of a loopback interface??
why is it used?

i also want to know about the route command,
 is it used to send specific incoming packets, to some specific 
destinations precisely?
if thats the case,  are gateways build using route command?

and also what is the role of ARP cache?
why do we need to maintain it?

regards peevee