While most video cards are of the PCIe format, video cards come in other formats as well, including PCI and AGP.
These additional formats are older standards and don't communicate with the CPU and other components as quickly as PCIe.
A video card is a piece of computer hardware that's rectangular in shape with numerous contacts on the bottom of the card and one or more ports on the side for connection to video displays and other devices.
The video card installs in an expansion slot on the motherboard.
Using a dedicated video card may improve overall system performance because it includes its own RAM, power regulators, and cooling so that the system RAM and CPU can be used for other things.
In Windows, the easiest way to see what video card you have is to use Device Manager (see how to get there here).
Opening the computer case is another option, allowing you to see for yourself what video card is installed.
Doing this is of course required if you plan to replace the video card, but just identifying information about it is best done through the software I mentioned above.
This option is wise for the average business and home user not interested in advanced graphics capabilities or the latest games.
Most motherboards with on-board video allow BIOS to disable the chip in order to make use of a video card installed to an expansion slot (see how to get to BIOS here).
In order to use the more advanced features like three dimensional graphics, a full display driver designed for that specific display adapter must be installed.