An air-supported (or air-inflated) structure is any permanent building that derives its structural integrity from the use of internal pressurized air to inflate a pliable material (i.e. structural fabric) envelope, so that air is the main support of the structure. It is usually dome-shaped, since this shape creates the greatest volume for the least amount of material. However, rectangular inflatables are also possible, such as the Airtecture Exhibition Hall constructed by Festo AG & Co.
The concept was popularized on a large scale by David H. Geiger with the United States pavilion at Expo '70 in Osaka, Japan in 1970.
To maintain structural integrity, the structure must be pressurized such that the internal pressure equals or exceeds any external pressure being applied to the structure (i.e. wind pressure). The structure does not have to be airtight to retain structural integrity—as long as the pressurization system that supplies internal pressure replaces any air leakage, the structure will remain stable. All access to the structure interior must be equipped with two sets of doors or revolving door (airlock). Air-supported structures are secured by heavy weights on the ground, ground anchors, attached to a foundation, or a combination of these.