Dongle

A dongle is a small piece of computer hardware that connects to a port on another device to provide it with additional functionality, or enable a pass-through to such a device that adds functionality.[1] In computing, the term was initially synonymous with software protection dongles—a form of hardware digital rights management in which a piece of software will only operate if a specified dongle—which typically contains a license key or some other cryptographic protection mechanism—is plugged into the computer while it is running.The term has since been applied to other forms of devices with a similar form factor, such as: There are varying accounts on the etymology of the word "dongle"; in a 1999 paper, P. B. Schneck stated that the origin was unclear, but that it was possibly a corruption of the word "dangle" (since these devices "dangle" from a port on a PC).Linguist Ben Zimmer noted that the claim was likely a by-product of their "tongue-in-cheek" marketing style, and "was so egregiously false that the company happily owned up to it as a marketing ploy when pressed by Eric S. Raymond, who maintains the Jargon File, an online lexicon of hacker slang.In the mid-to-late 2010s, the dongle form factor was extended to digital media players with a small, stick-like form factor—such as Chromecast and Fire TV Stick—that are designed to plug directly into an HDMI port on a television or AV receiver (powered via Micro USB connection to the television itself or an AC adapter), in contrast to a larger set-top box-style device.
A dongle (center, in white) allowing an ethernet cable (left, in grey) to be connected to a Thunderbolt port on a laptop (right).
A parallel port adapter
A Chromecast stick plugged into the HDMI port of a TV. The cable attached to the other end is the USB power supply.
YongleethernetThunderboltsoftware protection donglesdigital rights managementsoftwarelicense keyUSB-to-serialMobile High-Definition LinkBluetoothUSB flash drivesdigital media playersparallel portRainbow Technologiesurban legendBen ZimmerEric S. RaymondJargon Fileunauthorized usecopyingserial portChromecastFire TV StickAV receiverMicro USBset-top boxSingle-board computersIntel Compute StickCassette adaptersMP3 playersmartphoneCD playerPersonal FM transmittersportable media playerportable cassette playerFM radiofloppy diskhard diskCommodore 64Apple IINintendo DSGame Boy AdvanceRumble PakSD cardFlash drivesMobile broadband modemsNetwork interface controllersEmulatorRepurposingReverse engineering