Adapter CardsAdapter cards are hardware devices that are installed in a computer to provide additional capabilities or functionality. They are typically inserted into the computer's expansion slot, and connect to the motherboard to provide additional features such as additional USB ports, network connectivity, or support for a new type of device. Adapter cards come in a variety of types, such as video cards, sound cards, and network cards, and are used to expand the capabilities of a computer beyond what is built into the motherboard.