These plates are so big, they actually cover the entire surface of the planet. Even so, there are still locations where these plates come together and collide with one another. Scientists call this place a fault line. Tectonic plates move very slowly, only a few inches every year. Yet the collision between plates can be very dramatic.
Earthquakes are common symptoms of plate movement.
They occur when plates collide but neither one wants to yield the direction it's going. Take the San Andreas Fault for example. The San Andreas Fault is responsible for almost all earthquakes that occur in the California area and is the fault line between the North American and Pacific plate. For millions of years the Pacific plate has been trying to go north while the North American plate thinks south is a better way to go. Like two giants, they wrestle with each other, each trying to gain mastery.