A hot air balloon is a type of aircraft that uses heated air to rise and float in the sky. It consists of a large fabric envelope filled with hot air, which is lighter than the cooler air outside. A burner is used to heat the air inside the envelope, allowing the balloon to ascend. The balloon is typically tethered to a basket that carries passengers and equipment. As the air inside the envelope cools, the balloon descends. Pilots can control the altitude by adjusting the temperature of the air, making hot air ballooning a unique and enjoyable experience.