The Earth's crust is broken up into pieces called plates.
The crust moves because of movements deep inside the earth.
The convection currents move the plates.
Where convection currents diverge near the Earth's crust, plates move apart.
Where convection currents converge, plates move towards each other.
The movement of the plates, and the activity inside the Earth, is called plate tectonics.
The point where two plates meet is called a plate boundary.
Earthquakes and volcanoes are most likely to occur either on or near plate boundaries.