The lithosphere includes the Earth's crust and the uppermost part of the mantle. The lithosphere's thickness varies depending on whether you measure the thin new crust on the ocean floor or the old crust of an established land mass.
The Earth's lithosphere is broken into continental plates that move over time. Slight movements in the lithosphere can cause earthquakes when the plates bump against each other. "Litho" is from the Greek word lithos, meaning stone. "Sphere" is from the Greek word sphaira, meaning globe or ball. The solid outer crust of any celestial body can also be called the lithosphere. Scientists use robots to examine the lithosphere on Mars.