Stands for "Accelerated Graphics Port." This is a graphics card expansion port designed by Intel that resides on the motherboard of a computer. PCI graphics ports typically run at 33 MHz and have a maximum transfer rate of 132 MB/sec. AGP ports, on the other hand, run at 66 MHz and can transfer data up to 528 MB/sec. This allows games and applications to store and retrieve larger, more realistic 3D shapes and textures without slowing down the animation on the screen.
Additionally, AGP cards can store graphics in system memory rather than video memory, which also helps improve performance. Becuase of these advantages, AGP cards will typically have better performance per MB of VRAM than PCI graphics cards.