Expansion slots
allow you to "expand" the capabilities of your PC. You simply plug an
expansion card
into one of the empty expansion slots on your motherboard. The number of expansion slots on a motherboard varies. You may have anywhere
from 3 all the way up to 12 slots on your motherboard.
Expansion slots and cards come in different flavors including
8-bit,
16-bit,
32-bit,
and
PCMCIA.
The bit width of the slot or card determines how much data they can
communicate to the CPU at a time.