A mouthpiece is a device that fits into the mouth and is used for various purposes, such as playing musical instruments or protecting teeth. In music, mouthpieces are commonly found in instruments like trumpets and saxophones, where they help produce sound. In sports, mouthpieces are often used in activities like boxing and football to protect the teeth and jaw from injury. In addition to musical and sports applications, mouthpieces can also refer to dental devices. These are often used in orthodontics to help align teeth or in sleep medicine to prevent conditions like sleep apnea. Overall, mouthpieces serve important functions in both recreational and health-related contexts.