A creature or an object belongs to a size category: Tiny, Small, Medium, Large, Huge, or Gargantuan. A creature’s size determines how much space the creature occupies in combat. An object’s size affects its Hit Points. See also “Breaking Objects” and “Playing the Game” (“Combat”). Skill A skill is an area of specialization associated with an ability check. If you have proficiency in a skill, you can add your Proficiency Bonus when you make an ability check associated with that skill. See also “Playing the Game” (“Proficiency”).