Plate tectonics is the scientific theory that describes the large-scale movement of Earth's lithosphere, which is divided into several rigid plates. These plates float on the semi-fluid layer of the Earth's mantle and interact with each other at their boundaries. The movement of these plates is responsible for earthquakes, volcanic activity, mountain building, and the formation of ocean basins. Plate tectonics provides an explanation for many geological phenomena and helps scientists understand the dynamic processes that shape the Earth's surface. The theory was first proposed in the 1960s and has since become a fundamental concept in the field of geology.