Despite its apparent complexity, our world seems to be governed by simple laws of physics.This volume provides a philosophical introduction to such laws.I explain how they are connected to some of the central issues in philosophy, such as ontology, possibility, explanation, induction, counterfactuals, time, determinism, and fundamentality.I suggest that laws are fundamental facts that govern the world by constraining its physical possibilities.I examine three hallmarks of laws-simplicity, exactness, and objectivity-and discuss whether and how they may be associated with laws of physics.