In this article, I introduce some main strands in the philosophical debate on the nature of causation. I begin by sketching David Hume's influential discussion of causation (1739–1740). I then outline some modern descendants of Hume's regularity theory, most importantly the necessary and sufficient conditions approach, and counterfactual theories, highlighting along the way the various problems faced by such accounts. I then introduce the main competitor to these theories, namely process-based accounts, and end by discussing problematic cases of causation by absence.