Just about anything. That's the idea of an expansion card (it expands the functionality of a computer with a add-in card).
expantion cards
power supply motherboard RAM chipset cpu HDD/SSD graphics card optical drive expantion cards network interface controller sound canrd (expantion card) video card (expantion card) look at this wiki page- dft.ba/-custom-build
For computer yes.
cpu expantion slots memory chips hot sink
Nvivia video card.
Sound Card
Is an expantion slot that is connected to your motherboard. To create new ports on your computer. (Example: I instuled new usb port on my computer.
If you bought the computer - you would know if the card you used to pay for it was stolen or not !
Either someone has skimmed - copied your card when you used it. Or they've used a computer program to generate working card numbers and one of them was yours.
A network interface card is used to connect a computer to an Ethernet network
A video capture card is a card used to get a picture from a TV source such as cable or satellite to your computer. Now they make HDMI cables which hook up to your TV and your computer and it projects video and pictures to and from your computer.
You be referring to a CAC Card. This was a common access card, also used for computer security by the DoD and military that doubles as an ID Card in some cases. It's used for PKI (Public Key Infrastructure) encryption key holding as well in some cases.