The term used to describe the movement of tectonic plates is "plate tectonics." This geological theory explains how the Earth's outer shell, the lithosphere, is divided into several large and small plates that float on the semi-fluid asthenosphere beneath them. These plates are constantly moving, albeit slowly, and their interactions can lead to geological phenomena such as earthquakes, volcanic eruptions, and the formation of mountains. The movement occurs due to forces generated by the Earth's internal heat, convection currents in the mantle, and the gravitational pull on the plates. Understanding plate tectonics is crucial for comprehending Earth's geological history and processes.