There are 3 types of plate tectonic boundaries: Convergent, divergent, and transform. These are also known as destructive, constructive, and conservative. The outcome of these depends upon the material from which the plates involved are made from; there are two principal types: oceanic and continental.Convergent plate boundaries occur when two plates collide. Typically the plates are moving at each other, but it can occur in other circumstances; for example, if one plate is moving in the same direction as another but far more quickly, it causes the same effect. If two plates of the same type collide, this creates deep seafloor trenches or mountain ranges (such as the Himalayas). If there is one of each type, the oceanic plate (more dense) is subducted below the other and often leads to volcanic activity.Divergent plate boundaries occur when two plates are moving apart from one another. It creates new oceanic crust, and occurs in the middle of the Atlantic ocean (so technically we move a few cm away from N.America every year!).Transform plate boundaries occur when two plates are not colliding or moving apart, but moving sideways next to one another. The most famous example is the "San Andreas Fault" running through California, USA where the 1989 San Francisco earthquake occured.Regardless of plate type, earthquakes are common, and both convergent and divergent are associated with volcanic activity.