There are 3 different plate boundaries including divergent, convergent and transform.
Divergent boundaries occur primarily at mid ocean ridges where new oceanic crust is produced by the process of convection.
Convergent boundaries occur when 2 plates collide and the more dense plate (oceanic crust) is subducted (goes down). At this location, oceanic crust is destroyed and the geologic feature that forms is called a trench. That subducted rock remelts and will extrude as island arcs. Some convergent boundaries are between 2 continental plates and so neither plate is sufficiently dense to subduct. In this case, mountains will form; the most well known convergent/convergent boundary occurs in the Himalayan mountains.
Transform boundaries are where 2 plates slide laterally past each other. There is no vertical movement as in convergent or divergent motion. Crust is neither created nor destroyed. The best example of a transform boundary is the San Andreas fault in California.
