Depending which hardware component you are on about as they all have diffrent roles. But they all have the same function to communicate with the motherboard, this is done in a certain way I can't remember what its called.(sorry)
but each co,ponent has to communicate with the motherboard, as thats the main point for each connection. Its like when you call up a company, if you go to reception they act as the motherboard, they send you where your ment to go. The motherboard send the data round to the right places.
skip all that
main functions Input, output, PROCESS, and Storage and to communicate