Answer:
The theory of plate tectonics describes the movement of the plates across the Earth's lithosphere (the crust and upper mantle) through immense periods of time. Earth's litoshphere is composed of 7 (or 8, depending on how they are defined) major plates and many more minor plates.
The movement is attributed to different phenomena stemming from Earth's rotation, gravity, and mantle dynamics. All of these forces play a role in influencing the size, shape, and positioning of the different landmasses that currently shape our continents and islands.