The major driving force behind plate tectonics is mantle convection. The Earth's mantle experiences heat transfer due to the decay of radioactive elements and the residual heat from the planet's formation. This process creates convection currents that generate movement in the semi-fluid mantle layer, causing tectonic plates to shift. As plates interact at their boundaries, they can diverge, converge, or slide past each other, leading to geological phenomena such as earthquakes, volcanoes, and the formation of mountain ranges. Understanding plate tectonics is crucial for studying geological activity and the Earth's history.