Skill (Dungeons & Dragons)

Skills were introduced in the third edition of the Dungeons & Dragons role-playing game.

What is a Skill?
A skill is an ability a character can improve in by using skill points to increase one's rank in the skill.

Each skill is used for a different purpose and is usually self-explanatory. Some skills can only be taken by certain classes, such as Read Lips or Animal Empathy. These skills are called exclusive skills. Others can be used even if the character has no ranks in that skill (i.e. is not trained in that skill).

Each skill is tied to an ability, and the modifier for that ability affects how the skill is used, as outlined below.

How skills are used
Whenever a skill needs to be used, a player rolls a twenty-sided die and adds his ranks in the skill and his ability modifier for that specific skill (for example, Intelligence for Disable Device) to the result. This is called a skill check. Occasionally, spells or racial abilities also affect this number (such as an Elf's +2 to Search, Spot, and Listen checks).

Sometimes, a skill check may be aided by favorable circumstances (such as you brandishing a weapon while using Intimidate) or hampered by unfavorable circumstances (such as using improvised tools to pick a lock).

Regardless of circumstance, the Dungeon Master sets the target number for the task, called a Difficulty Class. If the check meets or exceeds this number, then that use of the skill was successful.

Reference
Monte Cook, Jonathan Tweet, Skip Williams. Player's Handbook (Wizards of the Coast, 2000).