A hot air balloon is a type of aircraft that uses a large fabric envelope filled with heated air to lift off the ground. The hot air inside the envelope is less dense than the cooler air outside, allowing the balloon to rise. A burner, fueled by propane, heats the air, and a pilot can control the altitude by adjusting the temperature. Hot air balloons are often used for recreational purposes, offering scenic views from above. They can be seen at festivals and events, where colorful balloons fill the sky. Safety measures, such as proper weather conditions and equipment checks, are essential for a successful flight.