# Penalty Stroke > Canonical: https://pinflag.io/glossary/penalty-stroke ## Penalty Stroke URL: https://pinflag.io/glossary/penalty-stroke > A penalty stroke is an extra stroke added to a golfer's score under the Rules of Golf, most commonly for a shot into a penalty area, a ball out of bounds, or a ball declared unplayable. A penalty stroke is the Rules of Golf's way of pricing an infraction the same way any other stroke counts — it simply adds to the score without a shot being played toward the hole. The most common triggers are a ball in a red or yellow penalty area, a ball out of bounds, and a ball declared unplayable, each with its own relief options and stroke cost. In strokes gained terms, a penalty is priced into the shot that caused it: the expected strokes at the new position are subtracted from the expected strokes at the start, the stroke just played is subtracted, and then the penalty stroke is subtracted again. A tee shot that finds the water doesn't just lose the distance it would have gained — it loses a full extra stroke on top, usually the single most expensive way to lose strokes gained on a hole. Because a penalty changes both the score and the position a golfer plays from next, it has to be recorded rather than skipped or averaged away for a strokes gained number to stay accurate. See also: [Strokes Gained Explained: The Complete Guide](https://pinflag.io/guides/strokes-gained)