The pixels you're now reading on your computer monitor are being refreshed at rates of 30 to 70 times per second. Although your screen is mainly black and white as you read this, it is potentially capable of producing up to 16.7 million different colours. And while your PC is probably not operating at top speed as you scan this article, it's likely capable of reaching data-transfer rates of one gigabyte per second. All these impressive figures are attributable to one hardware component in your computer: the graphics card.

Strictly speaking, the data-transfer rate of one gigabyte per second is performed by the actual application you're using. As you use a software program, it sends your commands to the computer's hardware, translating what your fingers type into the letters and numbers that appear on the screen before you.

Once the computer receives your keyboard commands, it shares them among its graphics card and its central processing unit (CPU). The graphics card is a sophisticated piece of hardware that includes its own store of RAM (random access memory) in order to perform its function of bringing images to life on your screen. There is a separate stash of RAM in the heart of your computer itself, which hangs onto your work as you fiddle with it; and this graphics-card RAM does essentially the same thing, while remaining dedicated to graphical data only. The graphics card can carry 16MB (megabytes) to 64MB of RAM (your PC's share of RAM is usually between 64MB and 128MB). Graphics-card RAM stores information that is not going onscreen instantaneously.

Once the graphics card holds the data destined for your monitor, it gets together with the CPU to make pictures that will light up your screen. The commands you type into your keyboard are received by the graphics card as binary code -- digital zeroes and ones that must be translated into the analog signals your screen can deal with. Before that information is translated into analog form, the graphics card and CPU enact two phases -- the transform and lighting phase, and the set-up phase.

The transform and lighting phase takes information from the software program you're using to assemble the screen's pixels and create lighting effects among them. The transform and lighting phase is often performed by the computer's CPU rather than its graphics card; although newer, flashier cards are able to handle even this part of the proceedings. From there, the graphics card always takes over to enact the set-up phase, in which the pixels stipulated in the previous step become plotted to particular points on the monitor. The first phase handles the colour, shade, and interlock of the pixels; the second phase oversees where on your screen those pixels appear.