Is there a compatability for video cards?

I want to change my video card and i want to if it has to ba compatible to my computer and if so how do i know what to buy?Is there a compatability for video cards?
of couse. ask the seller or your computer shopIs there a compatability for video cards?
There is PCI, PCIe and AGP slot types. AGP has voltage ratings from 1X, 2X-4X, and 8X. PCIe is just PCIe. PCI is out dated. Read up on the AGP voltage ratings if that is what you are running. Or if you are up to PCIe then your wallet is where you should be checking for upgrading because they are relatively new and there is only one compatable type.
3 types exsist

pci this is old tech

agp

pci express