In computing, a video card (also called a graphics card or a graphics accelerator) is a special circuit board that controls what is shown on a computer monitor and calculates 3D images and graphics.

A video card can handle two types of video images. First, they can be used to display a two-dimensional (2D) image like a Windowsdesktop, or a three-dimensional (3D) image like a computer game. Computer-Assisted Drawing (CAD) programs are often used by architects and designers to create 3D models on their computers. If a computer has a very fast video card, the architect can create very detailed 3D models.

Many computers have a basic video and graphics capabilities built-in to the computer's motherboard. These "onboard" video chips are not as fast as normal graphics cards. They are fast enough for basic computer use and even some basic computer games. If a computer user wants faster and more detailed graphics, a video card can be installed.

Video cards have their own processor (called a Graphics Processing Unit or GPU). The GPU separate from the main computer processor (called the Central Processing Unit or CPU). The CPU's job is to process all the calculations needed to make the computer function. The GPU's job is to handle 3D graphics calculations so the CPU does not have to. 3D graphics calculations take a lot of CPU power, so having a video card to handle the graphics calculations lets the CPU focus on other things like running computer programs.

Video cards also have their own memory, separate from the main computer memory. It is usually much faster than main computer memory, too. This helps the GPU do its graphics calculations even faster. Most video cards also allow more than one monitor to be plugged in at one time. This lets the computer user use more than one monitor at once. Graphics manufacturers nVidia and ATI have special technologies that allow two identical cards to be linked together in a single computer for much faster performance. nVidia calls their technology SLI and ATI calls their technology CrossFire. Some modern graphics cards can even process physics calculations to create even more realistic-looking 3D worlds.

Video cards typically connect to a motherboard using the Peripheral Component Interconnect (PCI), the Advanced Graphics Port (AGP) or the Peripheral Component Interconnect Express (PCI Express or PCI-E). PCI-E is the newest and fastest connection; most (if not all) new video cards and motherboards have this connection. Before PCI-E was used, AGP was the standard connection for video cards. Before AGP, video cards were designed for PCI (sometimes called "regular" PCI).