Plate Tectonics is a theory that almost all of the world's scientists believe is true. It involves tectonic plates: puzzle-like formations under the Earth's crust that are floating on a layer of magma called the mantle. The mantle is a layer of the earth. The crust is another, it is what we live on. Tectonic plates are part of a layer called the lithosphere. The lithosphere floats on a section of the upper mantle called the asthenosphere. The asthenosphere is a place where hot magma swirls in a convection current. This current causes the movement of the tectonic plates.
Tectonic plates are constantly moving around, colliding, and drifting apart. Sometimes one plate slides under the other. This is called subduction. Divergence means that two plates are sliding apart, and convergence is the opposite. Transform is when the edges of two plates slide along each other. When plates collide, it can cause earthquakes and tsunamis. Volcanoes, however, are more commonly caused by subduction, because when two plates part it allows the magma in the mantle to burst forth.