The lithosphere is the outermost layer of the Earth, consisting of the crust and the upper part of the mantle. It is a solid, rigid layer that forms the Earth's tectonic plates. The lithosphere is divided into several large and small plates that float on the semi-fluid asthenosphere below. These plates are constantly moving and interacting with each other, leading to processes such as earthquakes, volcanic eruptions, and the formation of mountain ranges.
The lithosphere is mainly composed of rocks, including granite and basalt. The crust, which forms the outermost part of the lithosphere, is made up of lighter rocks such as granite, while the upper mantle consists of denser rocks like basalt.