Unconscious

An unconscious creature is Incapacitated, can't move or speak, and is unaware of its surroundings.

• The creature drops whatever it's holding and falls prone.
• The creature automatically fails Strength and Dexterity saving throws.
• Attack rolls against the creature have Advantage.
• The creature's Dexterity modifier is not added to its AC.
• Any Attack that hits the creature is a Critical Hit if the attacker is within 5 feet of the creature.

Knocking a Creature Out

Sometimes an attacker wants to Incapacitate a foe, rather than deal a killing blow. When an attacker reduces a creature to 0 hit points with a melee attack, the attacker can knock the creature out. The attacker can make this choice the instant the damage is dealt. The creature falls unconscious and is Stable.

Player Character Unconsciousness

If Damage reduces you to 0 Hit Points and fails to kill you, you fall unconscious.
Whenever you are reduced to 0 hit points, you gain a level of Exhaustion.
This unconsciousness ends after 1 minute as long as you have at least one Hit Point, but you must recover from your Exhaustion through rest.
If you start your turn unconscious and at 0 hit points and are not Stable, you must make a Death Saving Throw.