1) A convergent plate boundary where two plates collide and one slides underneath the other, such as the Aleutian Islands in Alaska. 2) The three main types of plate boundaries are convergent boundaries where plates collide, divergent boundaries where plates move apart, and transform boundaries where plates slide past one another. 3) Plate tectonics involves the movement of plates across Earth's surface due to convection currents in the mantle, which causes the slow movement of the plates.