Damage Types
Playing the Game › Damage and Healing · SRD 5.2.1 p. 16
Each instance of damage has a type, like Fire or Slashing. Damage types are listed in “Rules Glossary” and have no rules of their own, but other rules, such as Resistance, rely on damage types.
Knocking Out a Creature
When you would reduce a creature to 0 Hit Points with a melee attack, you can instead reduce the creature to 1 Hit Point and give it the Unconscious condition. It then starts a Short Rest, at the end of which that condition ends on it. The condition ends early if the creature regains any Hit Points or if someone takes an action to administer first aid to it, making a successful DC 10 Wisdom (Medicine) check.