AGP: (Accelerated Graphics Port) is usually located near the white PCI slots on a Motherboard. This is where you install a video card for better graphical performance. Most motherboards now come with onboard sound and video which is top quality, however when you install AGP video it removes pressure from the computers resources. You will find that your computer will run faster as an AGP video card communicates directly with the processor and has its own memory.
PCI express video cards are another way to add video to your computer, however they compete with other components in the computer for precious resources.