Dead man's switch

The term dead man's switch originally referred to a mechanism that would disable machinery if its operator were to become somehow incapacitated. For example, falling asleep. A good example of dead man's switch is the button you have to hold down to start a lawn trimmer or mower.

Software equivalent

With software, a dead man's switch generally refers to an alert sent due to a lack of activity over a certain period. Various software can simulate a dead man's switch on your computer in different ways. One example is the automatic engagement of a lock screen after a period of user inactivity. An example of a longer term dead man's switch is Google's Inactive Account Manager that allows designation of a third-party to take control of an inactive account.

Fail-safe system, Security, Security terms