Birdie is a term commonly used to refer to a small bird, often characterized by its ability to fly and sing. Birds are warm-blooded vertebrates that belong to the class Aves. They have feathers, beaks, and lay eggs, making them distinct from other animal groups. In sports, particularly in golf, a "birdie" refers to a score that is one stroke under par on a hole. For example, if a golfer completes a hole in three strokes when the par is four, they achieve a birdie. This term is widely recognized among golf enthusiasts.