Final answer:
The Earth's lithosphere is divided into around twelve major tectonic plates which move due to convection currents in the asthenosphere, causing significant geological activity at their boundaries.
Step-by-step explanation:
Earth's lithosphere is divided into about a dozen major tectonic plates that fit together like pieces of a jigsaw puzzle. These plates cover the Earth's mantle, including both continental and oceanic crust. The movement of these plates is caused by convection currents in the underlying asthenosphere, and their interactions at plate boundaries can result in various geological phenomena such as earthquakes, volcanic activity, and mountain building.
The major types of plate boundaries are divergent, where plates move apart; convergent, where plates move towards each other and can lead to subduction; and transform, where plates slide past each other. The motion of the plates is relatively slow, typically ranging from millimeters to a few centimeters per year, a rate comparable to human fingernail growth.