A birdie in golf is when a player scores one stroke under par on a hole. For example, if a hole is a par-4 and a golfer finishes it in three strokes, that would be a birdie. The term originated in the early 20th century, with 'bird' being slang for something excellent.

Golfers aim for birdies as a way to improve their score, and achieving them regularly is a sign of a skilled player. The concept of par and under-par scoring is central to the sport of golf, with birdies representing a key measure of success.