Quadrature Encoder
Quadrature encoder, a type of rotary encoder, produces two outputs 90 degrees out of phase. By counting transitions of these outputs, a computer can decode the shaft's position and its direction of motion.

QWERTY Keyboard
QWERTY keyboard refers to the arrangement of keys on a standard English computer keyboard or typewriter.

QXGA: Quantum Extended Graphics Array
Quantum Extended Graphics Array (QXGA) is a display specification that is capable of supporting 2048 x 1536 resolution, or approximately 3.2 million pixels with a 4:3 aspect ratio. As of 2005, this is the highest non-experimental and non-widescreen resolution, and there are very few devices that can render images at such high resolution.