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Accelerated Graphics Port

AGP is short for Accelerated Graphics Port, a new interface specification
developed by Intel Corporation. AGP development was based on PCI (Peripheral Component Interconnect) , but is designed especially for the throughput demands of 3-D graphics. Rather than using the PCI bus (the common standard) for graphics data, AGP introduces a dedicated point-to-point channel so that the graphics controller can directly access main memory. The AGP channel is 32 bits wide and runs at 66 MHz. This translates into a total bandwidth of 266 MBps, as opposed to the PCI bandwidth of 133 MBps. AGP also supports two optional faster modes, with throughputs of 533 MBps and 1.07 GBps. In addition, AGP allows 3-D textures to be stored in main memory rather than video memory.

Definition provided by Webopedia (AGP).

AGP Card

AGP Slot

Specifications
Development
Evaluation Kit

Microsoft's Views

AGP technology allows textures to be stored in system memory, enabling larger, detailed texture maps in consumer applications. Effective AGP implementations can eliminate the need for a local memory texture cache.

Support the following when implementing AGP support under Microsoft® Windows®
operating systems:

Comply with the PCI Bus Power Management Interface Specification, Revision 1.0
or later, including the Configuration Space registers and the device state (Dx) definitions.

     Comply with PCI 2.1 software interface layers, including the implementation of
     Subsystem ID and Subsystem Vendor ID
     Comply with Accelerated Graphics Port Interface Specification, Revision 1.0 or later.
     This means the card has an AGP capability pointer with a working AGP capability
     structure that has the following characteristics:
          A minimum request-queue depth of 1 DWORD (RQ value of 0)
          A workable AGP_ENABLE
          A minimum speed of 2x, system implementation of GART, and support for
          non-local video memory are required for all system types except mobile PCs

More Info:

AGP Comparisons
PcGuide's Technical Data

Glossary

Throughput - the amount of data transferred from one place to another or processed in a specified amount of time. Data transfer rates for disk drives and networks are measured in terms of throughput. Typically, throughputs are measured in Kbps, Mbps and Gbps.

Channel - a collection of wires and protocols that allows the expansion of a computer by inserting printed circuit boards (expansion boards).

Controller - a device that controls the transfer of data from a computer to a peripheral device and vice versa.

Main Memory - refers to physical memory that is internal to the computer. The word main is used to distinguish it from external mass storage devices such as disk drives. Another term for main memory is RAM.

MHz - abbreviation for megahertz. One MHz represents one million cycles per second.

Bandwidth - the amount of data that can be transmitted in a fixed amount of time. For digital devices, the bandwidth is usually expressed in bits per second(bps) or bytes per second. For analog devices, the bandwidth is expressed in cycles per second, or Hertz (Hz).

MBps - Short for megabytes per second, a measure of data transfer speed. Mass storage devices are generally measured in MBps.