AirDrop is an ad-hoc service in Apple Inc.'s OS X and iOS operating systems, introduced in Mac OS X Lion (OS X 10.7) and iOS 7, that enables the transfer of documents among supported Macintosh computers and iOS devices without using mail or a mass storage device. OS X (prior to Yosemite) and iOS (prior to iOS 8) use different AirDrop protocols and are not interoperable with pre-release versions of Yosemite.