1) A GPU is a computer chip that performs rapid mathematical calculations primarily for rendering images, allowing graphics processing to be offloaded from the CPU.
2) Graphics cards have their own memory and processing capabilities, making them almost independent from the CPU. They output video through ports like DVI, VGA, and HDMI.
3) Computer monitors display the images generated by the graphics card. Resolution and aspect ratio can vary between monitors. DVI connections are preferred over VGA as they transmit digital signals without conversion.