Introduction to plate tectonics
Tectonic plates are the most outer layer of the earth's lithosphere and are divided into two types, oceanic and continental (This does not mean that land is always continental nor is the ocean always on the oceanic crust). These plates move towards each other (Converging) and away from each other (Diverging). This movement is known as continental drift, where the convection currents of the earth's mantle (consists of magma) move these heavy plates. This movement then cause earthquakes and volcanic eruptions.
The earth
The most outer part of the earth is the lithosphere, this is where the oceanic crusts and continental crusts meet.
The second picture shows how convection currents move crust towards and away from each other.
The second picture shows how convection currents move crust towards and away from each other.