What is the term for a narrow slot on the motherboard where an expansion card can be inserted?

The term for a narrow slot on the motherboard designated for the insertion of an expansion card is known as an expansion slot. This term encompasses various types of slots that allow for the addition of hardware components to enhance the functionality of a computer, such as graphics cards, sound cards, or network cards. Expansion slots provide the necessary connections to the motherboard, enabling communication between the new hardware and the system.

While PCI and AGP slots are specific types of expansion slots, the broader term "expansion slot" accurately describes any location where an additional card can be added to expand the computer's capabilities. USB ports, on the other hand, are not designated for expansion cards but rather serve as connection points for peripherals like mice, keyboards, and external drives. Thus, "expansion slot" is the most inclusive and correct term for this query.