A stratospheric balloon is a large, helium-filled balloon designed to reach the stratosphere, which is the second layer of Earth's atmosphere. These balloons can ascend to altitudes of about 20 to 40 kilometers (12 to 25 miles) and are often used for scientific research, weather monitoring, and technology testing. The payload attached to the balloon can include instruments for collecting data on atmospheric conditions, radiation levels, and other environmental factors. Stratospheric balloons are also utilized by organizations like NASA and universities for educational purposes and to conduct experiments that would be difficult to perform at ground level.