Dongle

A dongle is a small hardware device that connects to a computer, often to authenticate a piece of software. When the dongle is not present, the software runs in a restricted mode or refuses to run. Dongles are used by some proprietary vendors as a form of copy prevention or digital rights management because it is much harder to copy the dongle than to copy the software it authenticates. Vendors of software protection dongles (and dongle-controlled software) often use terms such as hardware key, hardware token, or security device in their written literature. In day-to-day use however, the jargon word "dongle" is much more commonly used.