Here's a breakdown:

* Fault: A fracture in the Earth's crust where rocks on either side have moved relative to each other.

* Types of Movement: Faults can move in different directions:

* Strike-slip fault: Rocks move horizontally past each other. Think of sliding two books past each other on a table.

* Dip-slip fault: Rocks move vertically past each other. Think of pulling two books apart on a table.

* Oblique-slip fault: A combination of horizontal and vertical movement.

Key Points:

* Movement: The key element is that the rocks on either side of the fault are displaced relative to each other.

* Stress: Faults are formed due to stress within the Earth's crust.

* Earthquakes: Movement along faults is the primary cause of earthquakes.

Let me know if you'd like more details about specific types of faults or the process of fault formation.