A video card, video adapter, graphics-accelerator card, display adapter, or graphics card is an expansion card whose function is to generate and output images to a display. Many video cards offer added functions, such as accelerated rendering of 3D scenes, video capture, TV-tuner adapter, MPEG-2 and MPEG-4 decoding, FireWire, light pen, TV output, or the ability to connect multiple monitors, while other modern high performance cards are used for more graphically demanding purposes such as PC games.

A video card (also known as a display adapter or graphics card) is what allows video to be processed and sent to a monitor or other display. Most displays and video adapters adhere to a standard called Video Graphics Array (VGA), which is an analog connection type communicating the resolution and colors to the monitor. There is a new display standard becoming popular called Digital Visual Interface (DVI), with some manufacturers offering DVI-only video cards. Many new displays (like LCDs and high-end TV displays) have DVI connections, but typically have an adapter to use the older VGA connector if your video card does not support DVI. DVI does provide a higher quality signal, especially noticeable on a digital display such as an LCD.

Video Cards can be found in different types of interfaces, with many motherboards including built-in onboard video without requiring an addon card. The newest type of video card is "PCI Express" (PCIe). PCIe comes in varying "speeds" for example 1x, or 4x, or 16x. Different speed PCIe connections will have differently sized connectors, with larger speeds having larger connectors. Any PCIe card can plug into a PCIe slot that is at least as large as the card is rated at, for example: You can plug a 1x card into a 16x slot, though the card will still only function at 1x, but you cannot plug a 16x card into a 1x slot. PCIe is a high performance general-purpose slot that can be used for hardware other than video cards as well. Accelerated Graphics Port (AGP) is the most common existing video card slot type, but is being replaced by PCIe in newer motherboards. AGP is only for video, it is not a general-purpose type of slot. AGP Video cards are still a big seller, and are still a very good choice for gaming, with many high-end cards being available in AGP. Older video card connection types like PCI and ISA are being quickly phased out, though there are still a few manufacturers making relatively high performance PCI cards.

Video Cards are a high performance device so regularly maintaining up to date drivers for your card is highly recommended, especially for gamers.

Video memory
Type Memory clock rate (MHz) Bandwidth (GB/s)
DDR 166 - 950 1.2 - 30.4
DDR2 533 - 1000 8.5 - 16
GDDR3 700 - 2400 5.6 - 156.6
GDDR4 2000 - 3600 128 - 200
GDDR5 3400 - 5600 130 - 230

The memory capacity of most modern video cards ranges from 128 MB to 4 GB, though very few cards actually go over 1 GB.[8][9] Since video memory needs to be accessed by the GPU and the display circuitry, it often uses special high-speed or multi-port memory, such as VRAM, WRAM, SGRAM, etc. Around 2003, the video memory was typically based on DDR technology. During and after that year, manufacturers moved towards DDR2, GDDR3, GDDR4, and even GDDR5 utilized most notably by the ATI Radeon HD 4870. The effective memory clock rate in modern cards is generally between 400 MHz and 3.8 GHz.

Video memory may be used for storing other data as well as the screen image, such as the Z-buffer, which manages the depth coordinates in 3D graphics, textures, vertex buffers, and compiled shader programs.