Unconscious
An unconscious creature is incapacitated.
The creature immediately drops what they're holding and falls prone.
An unconscious creature loses awareness of their surroundings. They cannot speak or make any voluntary movement.
Attacks against the unconscious creature have advantage.
Any attack that hits an unconscious creature that is either a melee attack or made from within 5 ft. is a critical hit.
Click here for a note about ranged attacks (7).
Notes
A ranged attack made from 30 ft. away against a paralyzed target has advantage.
A ranged attack made from 30 ft. away against an unconscious target has advantage and disadvantage (because the unconscious creature is prone). In this case, the attack is rolled without advantage or disadvantage.
A ranged attack made from within 5 ft. against a paralyzed or unconscious creature has advantage and disadvantage. The attack is rolled without advantage or disadvantage. Such a ranged attack becomes a critical hit as long as it hits.