What is the difference between modus ponens and modus tollens in deductive reasoning?

Modus ponens is a deductive reasoning rule that affirms the consequent, while modus tollens is a rule that denies the antecedent. In simpler terms, modus ponens says if A then B, and B is true, so A must be true. Modus tollens says if A then B, but B is false, so A must be false.