An inner tube is a flexible, inflatable rubber or plastic cylinder that fits inside a tire. It holds air and provides cushioning, allowing vehicles like bicycles, motorcycles, and cars to roll smoothly over surfaces. When the outer tire is punctured, the inner tube can often be repaired or replaced, making it a practical component in many types of vehicles. Inner tubes are commonly used in various recreational activities, such as tubing down rivers or water parks. They come in different sizes and shapes, designed for specific uses, including swimming and snow tubing. Their lightweight nature makes them easy to transport and store.