Volcanoes form where magma from the Earth's interior makes its way to the surface. This mainly happens along plate boundaries—either where plates drift apart (e.g., mid-ocean ridges) or collide (subduction zones).

In the Earth's mantle, magma is created by high temperature and pressure. The magma rises, collects in a magma chamber, and when the pressure becomes too high, it searches for a way upward.

Special places called hotspots, like Hawaii (in the middle of a plate), can also cause volcanoes to form.