Expansion Slot is just like port into which expansion card can be inserted. In otherwords port is female and card is male.

to expand things that need expansion ;)

The expansion slot is the socket on the motherboard that can hold an adapter card. There are different types of expansion slots (pci, pcie, pciex16) so you need to check that the expansion is the same kind as the adapter card.

Aka: riser card. A riser card is a circuit board containing expansion slot(s) which allows expansion card(s) to be re-oriented and/or moved to another position relative to the motherboard. A typical riser card rotates an expansion card/slot through 90 degrees so that the card/slot is parallel to the motherboard. A riser card may be used to: - Rotate an expansion card through 90 degrees to face left or face right. - Shiftposition of an expansion card up and/or sideways.

Aka: riser card. A riser card is a circuit board containing expansion slot(s) which allows expansion card(s) to be re-oriented and/or moved to another position relative to the motherboard. A typical riser card rotates an expansion card/slot through 90 degrees so that the card/slot is parallel to the motherboard. A riser card may be used to: - Rotate an expansion card through 90 degrees to face left or face right. - Shiftposition of an expansion card up and/or sideways.