One of the most important pieces of technology in the "Star Trek" universe, the replicator is used primarily to provide food and water on board starships, thus eliminating the need to stock most provisions. (Starships, starbases, and other installations stock some provisions for emergency use, in case of replicator failure or an energy crisis.) On "", it was established that as long as there is an energy source to power life support, replication is used to provide breathable air on ships and starbases (and to disassemble the carbon dioxide exhaled by the crew), thus providing a seemingly endless supply of oxygen and eliminating the need to carry air tanks.