AirDrop


AirDrop is an ad-hoc service in Apple Inc.'s iOS and macOS operating systems, introduced in Mac OS X Lion and iOS 7, which enables the transfer of files among supported Macintosh computers and iOS devices without using e-mail or a mass storage device.
Prior to OS X Yosemite, and under OS X Lion, Mountain Lion, and Mavericks the AirDrop protocol in macOS was different from the AirDrop protocol of iOS, and the two were therefore not interoperable. OS X Yosemite and later support the iOS AirDrop protocol, which is used for transfers between a Mac and an iOS device as well as between two 2012 or newer Mac computers, and which uses both Wi-Fi and Bluetooth. This feature has been discontinued in macOS Catalina.
There is no restriction on the size of the file which AirDrop will accommodate.

Routine

iOS

On iOS 7 and later, AirDrop can be accessed by either tapping on Settings > General > AirDrop, or swiping up the home screen through Control Center. Both Wi-Fi and Bluetooth are automatically switched on when AirDrop is enabled as they are both utilized.
Options for controlling AirDrop discovery by other devices include:
In iOS 7 or later, if an application implements AirDrop support, it is available through the share button. AirDrop is subject to a number of restrictions on iOS, such as the inability to share music or videos from the native apps.

macOS

On Macs running macOS with Mac OS X 10.7 and greater, AirDrop is available in the Finder window sidebar. On Macs running OS X 10.8.1 or later, it can also be accessed through the menu option Go → AirDrop or by pressing ++.
Wi-Fi must be turned on in order for AirDrop to recognize the other device. The other device must also have AirDrop selected in a Finder window sidebar to be able to transfer files. Furthermore, files are not automatically accepted; the receiving user must accept the transfer. This is done to improve security and privacy.

System limitations

Transfer between two iOS devices

Running iOS 7 or later:
AirDrop can be enabled unofficially on iPad. Although not supported by default, AirDrop can be enabled by jailbreaking the device and installing "AirDrop Enabler 7.0+" from Cydia. This procedure is not supported or recommended by Apple, as engaging in jailbreaking can cause software instability, and introduce viruses.

Transfer between two Mac computers

Running Mac OS X Lion or later:
To transfer files between a Mac and an iPhone, iPad or iPod touch, the following minimum requirements have to be met: All iOS devices with AirDrop are supported with iOS 8 or later:
Running OS X Yosemite or later:
Bluetooth and Wi-Fi have to be turned on for both Mac and iOS devices.

Security and privacy

AirDrop uses TLS encryption over a direct Apple-created peer-to-peer Wi-Fi connection for transferring files. The Wi-Fi radios of the source and target devices communicate directly without using an Internet connection or Wi-Fi Access Point.
The technical details of AirDrop and the proprietary peer-to-peer Wi-Fi protocol called Apple Wireless Direct Link have been reverse engineered and the resulting open source implementations published as OWL
and OpenDrop.
There have been numerous reported cases where iOS device users with AirDrop privacy set to “Everyone” have received unwanted files from nearby strangers; the phenomenon has been termed "cyber-flashing." Users have the full ability to control their AirDrop settings and limit who can send them files, with options for "Everyone", "Contacts Only", or "Off". iOS 13 no longer shows Thumbnails on the prompt when receiving images sent by strangers.