Which type of cards allows expansion cards to plug into them instead of directly into the motherboard?

Riser cards serve a specific function in computer architecture, allowing expansion cards to be plugged into them instead of directly into the motherboard. This type of card is essential in scenarios where space is limited or when you want to add additional expansion slots without increasing the size of the motherboard.

Riser cards are particularly useful in compact server cases or certain desktop setups, where vertically stacking two or more cards can be more effective than placing them side by side. By facilitating a perpendicular orientation, riser cards maximize available space and enable better airflow within the system. They essentially provide a flexible solution for expanding a system's capabilities while maintaining an efficient design.