need of increasing nic cards

Hai Everybody,
i am new to this group.But i think i can find
right things at here.once my friend tod me abt using multiple nic
cards.she said that in the product they r designing they supported 8
nic's earlier now they want to increase.i was unable to know the need
and advantage of using multiple nic's.how can it reduce the load on
servers.....i think i can find a answer here.