Plate tectonics is the scientific theory that explains the movement of Earth's lithosphere. The lithosphere is divided into several large and small plates that float on the semi-fluid asthenosphere beneath them. These plates are constantly moving, colliding, and sliding past each other which causes earthquakes, volcanic activity, and the formation of mountain ranges. There are three main types of plate boundaries: divergent, convergent, and transform boundaries. At divergent boundaries, plates move away from each other, creating new oceanic crust and mid-ocean ridges. Convergent boundaries are where plates collide, leading to subduction zones, volcanic arcs, and mountain formation. Transform boundaries are where plates slide past each other horizontally, causing earthquakes like the San Andreas Fault in California. Plate tectonics not only influences geological processes but also plays a significant role in shaping Earth's surface and affecting ecosystems. The theory of plate tectonics has revolutionized the field of geology by providing a comprehensive explanation for various geological phenomena and helping scientists understand the dynamic nature of our planet.