Expansion card

An  expansion card in computing is a printed circuit board that can be inserted into an
expansion slot of a computer motherboard to add additional functionality  to a computer system.
One edge of the expansion card holds the contacts that fit exactly into the slot. They establish the
electrical contact between the electronics (mostly integrated circuits) on the card and on the
motherboard.
Connectors mounted on the bracket allow the connection of external devices to the card.
Depending on the form factor of the motherboard and case, around one to seven expansion cards
can be added to a computer system. There are also other factors involved in expansion card
capacity. For example, some expansion cards need two slots like  some Nvidia Get Force FX
graphics cards and there is often a space left to aid cooling on some high-end cards.