What does ground speed represent in aviation terminology?

Ground speed in aviation refers to the actual speed at which an aircraft is moving over the ground. It is a critical metric for pilots as it indicates how quickly they are covering distance relative to the earth's surface, which is different from airspeed, the speed of the aircraft through the air. Ground speed is influenced by factors such as wind conditions; a tailwind increases ground speed, while a headwind decreases it. Understanding ground speed is essential for navigation, fuel planning, and estimating arrival times, making it a fundamental concept in aviation operations.

The other options describe different aviation parameters that relate to altitude and pressure, which do not pertain to the speed over ground.