Conditions

Conditions alter a creature's capabilities in a variety of ways and can arise as a result of a spell, a class feature, a monster's attack, or other effect. Most conditions, such as blinded, are impairments, but a few, such as invisible, can be advantageous.
A condition lasts either until it is countered (the prone condition is countered by standing up, for example) or for a duration specified by the effect that imposed the condition.
If multiple effects impose the same condition on a creature, each instance of the condition has its own duration, but the condition's effects don't get worse. A creature either has a condition or doesn't.
The following definitions specify what happens to a creature while it is subjected to a condition.

Blinded

Charmed

Deafened

Exhaustion

Some special abilities and environmental hazards, such as starvation and the long-term effects of freezing or scorching temperatures, can lead to a special condition called exhaustion. Exhaustion is measured in six levels. An effect can give a creature one or more levels of exhaustion, as specified in the effect's description.

Level Effect
1 Disadvantage on ability checks
2 Speed halved
3 Disadvantage on attack rolls and saving throws
4 Hit point maximum halved
5 Speed reduced to 0

If an already exhausted creature suffers another effect that causes exhaustion, its current level of exhaustion increases by the amount specified in the effect's description.
A creature suffers the effect of its current level of exhaustion as well as all lower levels. For example, a creature suffering level 2 exhaustion has its speed halved and has disadvantage on ability checks.
An effect that removes exhaustion reduces its level as specified in the effect's description, with all exhaustion effects ending if a creature's exhaustion level is reduced below 1.
Finishing a long rest reduces a creature's exhaustion level by 1, provided that the creature has also ingested some food and drink.

Frightened

Grappled

Incapacitated

Invisible

Paralyzed

Petrified

Poisoned

Prone

Restrained

Stunned

Unconscious