What is the outer shell of Earth that includes tectonic plates called?

The outer shell of the Earth that includes tectonic plates is called the lithosphere. This layer consists of the crust and the upper part of the mantle, and is characterized by its rigid structure. The lithosphere plays a critical role in geology, as tectonic plates, which float on the semi-fluid asthenosphere beneath them, are responsible for seismic activity and the formation of various geological features, including mountains and oceanic trenches.

This concept is vital in understanding plate tectonics and how the Earth's landforms are shaped over geological time. The lithosphere's interaction with the underlying asthenosphere leads to the movement of these tectonic plates, causing phenomena such as earthquakes and volcanic eruptions. Recognizing the importance of the lithosphere is crucial for comprehending various Earth science concepts.