As giant slabs of the Earth’s lithosphere move around the planet, they are subjected to stress. Rocks respond to that stress by bending without breaking (plastic deformation), folding, or breaking (brittle deformation). They also form faults in response to pressure. The most common plate-boundary types of stress are compression at convergent boundaries, tension at divergent boundaries, and shear at transform faults.
When two plates collide, they experience compression stress at their convergent boundary. That type of stress causes rocks to fold and crumple as they push against each other, which leads to mountain ranges like the Himalayas. It also can lead to the thickening of the crust at the collision zone and to earthquakes along strike-slip faults.
At divergent plate boundaries, rocks are under a lot of tension because the plates are moving away from each other. This tension can cause magma to rise into gaps in the crust. It can also cause faults to develop in the crust, like a ridge or a canyon. Finally, it can cause earthquakes on a strike-slip fault, like the San Andreas Fault.
When two plates are sliding past each other, there’s a lot of shear stress. That’s the kind of stress that can cause blocky shapes to form in the Earth’s crust, such as horsts and grabens. It can also cause shallow earthquakes on a strike-slip or a normal fault, as well as more deep quakes along thrust faults.