Ability check

Ability checks are dice rolls that determine whether a creature succeeds or fails at a task. When attempting an ability check, a creature rolls a d20, and then adds the relevant ability score modifier and, if applicable, proficiency bonus to the results of the roll. If the final results equal or exceeds a target Difficulty Class (DC), specific to that task, it is considered as success.

Calculation:  d20 + Ability Score Modifier + (when applicable) proficiency Bonus

Skills and proficiency

Strength Athletics	Dexterity Acrobatics Sleight of Hand Stealth	Constitution -	Intelligence Arcana History Investigation Nature Religion	Wisdom Animal Handling Insight Medicine Perception Survival	Charisma Deception Intimidation Performance Persuasion

List of skills, sorted by ability score

Ability score	Skills
Strength	Athletics
Dexterity	Acrobatics Sleight of Hand Stealth
Constitution	(none)
Intelligence	Arcana History Investigation Nature Religion
Wisdom	Animal Handling Insight Medicine Perception Survival
Charisma	Deception Intimidation Performance Persuasion

Most ability checks are associated with a specific skill. If a creature is proficient with an ability check's associated skill, they may add their proficiency bonus to the results of that roll, in addition to the relevant ability score modifier. These rolls are often referred to as skill checks by the community, although they are not referred to as such in-game.

Proficiency Bonus Chart

Level	Proficiency Bonus
1 to 4	+ 2
5 to 8	+ 3
9 to 12	+ 4

Expertise

Expertise in a skill allows a creature to add double its proficiency bonus. Expertise usually comes from specific class features.

Automatic rolls

Some ability checks are automatic. For example, when a creature approaches an unactivated trap, the game rolls a Perception ability check to determine whether the creation notices the trap. Perception is a Wisdom Skill, so the character adds their Wisdom modifier and, if proficient in Perception, their proficiency bonus to the ability check. Once the trap is discovered, the character can interact with it to attempt to Disarm it, which requires a successful Sleight of Hand check, a Dexterity Skill.

Ability checks during dialogue

Ability checks are also common during dialogue, where some responses require a ability check to determine the outcome. Examples include using Charisma-based skills like Persuasion, Deception or Intimidation to influence others, or Intelligence-based Skills like Investigation, History or Religion to determine or remember facts.

Contests

A contest is a special type of ability check in which two creatures both roll an ability check to oppose each other, and one wins over the other. The creatures don't necessarily roll the same type of check.

An example of this is the  Shove action. The creature attempting the Shove rolls Athletics, and the defending creature rolls either Athletics or Acrobatics (the game chooses the Skill with the highest bonus) to contest the Shove. If the attacker's roll is higher than the defender's, the Shove succeeds; otherwise it fails.