Dying

Falling Unconscious

If damage reduces you to 0 hit points and fails to kill you, you fall unconscious. This unconsciousness ends if you reach maximum hit points. The creature is considered dying upon dropping to 0 hit point for the first time until it is stable or dead.

Death Saving Throws

Whenever you start your turn while dying, you must make a death saving throw, to determine whether you creep closer to death or hang onto life. DC15 Death Saving Throw is required to gain a success, otherwise you fail, On your third success, you become stable (see below). On your third failure, you die. The number of both is reset to zero when you are no longer dying.

Rolling 1 or 20

When you make a death saving throw and roll a 1 on the d20, it counts as two failures. If you roll a 20 on the d20, it counts as two successes

Damage and Healing while Dying

If you take any damage while you have 0 hit points, it is kept track of as negative hit points, as well as you loose (if any) 1 successful death saving throw and 2 successful death saving throws on a crit. If you reach negative hit points equal to your maximum hit points you die. If you receive healing, it counts as 1 successful death saving throw as well as increase your hit points.

Stabilizing a Creature

You can use your action to administer first aid to an unconscious creature and attempt to stabilize it, which requires a successful DC 15 Wisdom (Medicine) check which will give the creature 1 successful death saving throw.

A stable creature doesn't make death saving throws, but it does remain unconscious. The creature stops being stable, and must start making death saving throws again, if it takes any damage, however both successes and fails are reset. A stable creature that isn't brought to maximum hit point becomes conscious in 1d4 minutes after becoming stable.

Aftereffects

After becoming stable a creature is treated as if it has 3 levels of exhaustion – which can be removed the same way normal exhaustion is removed as well as: a short rest removes 2 levels of exhaustion (only the first short rest counts), a long rest removes all 3 levels of exhaustion.