Final answer:
The Earth's outermost layer is the lithosphere, which is composed of the crust and uppermost part of the mantle. It is divided into plates that interact and move, causing geological processes.
Step-by-step explanation:
The Earth's outermost layer is the lithosphere. It is composed of the crust and the uppermost part of the mantle. The lithosphere is divided into several large and small plates that float on the semi-fluid asthenosphere beneath. These plates interact and move, resulting in processes like earthquakes, volcanic activity, and the formation of mountains.
Learn more about Earth's outermost layer