Plate

In geology, a tectonic plate is a large, rigid piece of Earth's outer shell, called the lithosphere. These plates are big slabs that float on the semi-fluid layer beneath them, called the asthenosphere. They move slowly over Earth's surface, and their interactions—such as colliding, pulling apart, or sliding past each other—cause earthquakes, volcanic activity, and the creation of mountain ranges. Think of Earth's crust like a cracked egg shell made of several jigsaw-like pieces that are always shifting very gradually.