Graphical Processing Unit (GPU)

• The GPU is the "brain" of the graphics card. The GPU handles processing all of the data sent to the graphics card, from images to complex 3D shading, then sends them to the monitor to be displayed.
  
  

BIOS (Basic Input/Ouput System)

• The BIOS is essentially the instructions the computer needs to know how to use the graphics card. Without BIOS, both hardware and software would be unable to interact with a graphics card.
  
  

Memory

• Graphics cards have their own memory banks, called video memory. Graphics cards typically don't have more than 1 Gigabyte (GB) of RAM, but there are a few higher-end graphics cards on the market with considerably more memory. The memory allows the GPU to store information for use or manipulation.
  
  

Outputs

• As more and more monitor options have become available, graphics cards have had to keep up by utilizing more and different types out output connections. The VGA plug was the standard for a long time, but now new formats have been introduced such as S-Video, DMI and HDMI, which allow for better graphical displays on these monitors.
  
  

Cooling

• While cooling isn't much of an issue for a lower-end graphics card, it can be an essential component to high-end graphics cards. Processing complex 3D images can generate immense amounts of heat, often necessitating a means to cool the graphics card to keep from damaging the computer. Heat sinks and fans are the most common methods.