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 users to transfer files among supported Mac computers and iOS mobile devices without using email 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. The Yosemite released version (version 10.10) of OS X is compatible with previous versions of AirDrop. AirDrop in OS X operates over Wi-Fi, whereas the iOS implementation utilizes both Wi-Fi and Bluetooth. There is currently no restriction on file sizes that can be sent over AirDrop. Apple users have reported movie files over 10 GB being sent over AirDrop without any problems. The two computers need to be within 10 meters of each other for AirDrop to recognize the other party. To date only a small number of applications implement the AirDrop facility.