Whistling is the act of producing a sound by forcing air through a small opening, typically between pursed lips or through the teeth. This sound can vary in pitch and tone depending on the shape of the mouth and the force of the airflow. Whistling is often used as a form of communication, a way to express emotions, or simply as a musical expression. Many cultures around the world have developed unique whistling techniques, such as whistled languages that can convey complex messages over long distances. Whistling can also be found in various forms of music, where it serves as an instrument or embellishment, adding a playful or melodic element to a song.