Large airtight bag filled with hot air or a lighter-than-air gas such as helium or hydrogen that can rise and float in the atmosphere.
Experimental attempts may have begun by 1709, but not until 1783 did J.-M. and J.-É. Auguste Piccard to gather high-altitude data. The first round-the-world balloon flight was achieved in 1999 by Bertrand Piccard and Brian Jones. See also {{link=airship">airship .