Expansion card

Updated: 07/06/2021 by Computer Hope

Alternatively referred to as an add-on card, expansion board, internal card, interface adapter, or card, an expansion card is a PCB that fits into an expansion slot on a desktop computer. An expansion card is used to give a computer additional capabilities, such as enhanced video performance via a graphics card.


Expansion cards can sometimes be called daughterboards. However, it is more appropriate to refer to them as expansion cards or one of the terms mentioned earlier.

Types of expansion cards in a computer


The above devices are available as expansion cards and can also be onboard the motherboard.


See our expansion slot page for a listing of the slots these cards can use.

Expansion card example

Below is a graphic illustration of an ISA Modem expansion card (click the picture to get a descriptive overview).

Internal modem expansion card

As seen in the picture, an expansion card has two main parts, the gold plated connector that connects to a motherboard expansion slot and the connector plate. The back metal plate often has connections that allow an outside device to communicate with the card and computer. In this example, the modem has two RJ-11 jacks that allow it to communicate over a phone line.

Do laptops or netbooks have expansion cards?

Laptops, netbooks, and other mobile computers do not have expansion cards like what was explained above. However, some laptops can have PC Cards that can be inserted into the side of the laptop. They may also have a Cardbus slot for an ExpressCard to be added.

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