What is the difference between correlation and causation?

**Correlation** — two variables change together (positive or negative relationship)
**Causation** — one variable directly causes the change in another

Correlation does NOT imply causation!

Example: Ice cream sales and drowning rates are correlated (both increase in summer). But eating ice cream does not cause drowning — the hidden variable is summer/heat.

To establish causation you need controlled experiments or causal inference methods.