1. Compression: This is a stress that pushes or squeezes rocks together. It's like squeezing a sponge. Compression can cause rocks to fold, fracture, or even change their mineral composition.

2. Tension: This stress pulls or stretches rocks apart. It's like pulling on a rubber band. Tension can cause rocks to crack and break, leading to the formation of faults.

3. Shear: This stress causes rocks to slide past each other in opposite directions. It's like pushing a deck of cards sideways. Shear stress can also cause rocks to fracture and fault.

These three stresses, along with pressure, are responsible for the formation of many of the geological features we see on Earth, from mountains to valleys to earthquakes.