A kill switch is a mechanism used to shut down or disable machinery or a device or program. The purpose of a kill switch is usually either to prevent theft of a machine or data or as a means of shutting down machinery in an emergency. In manufacturing, for example, a kill switch (also called a big red button) might be used to shut down machinery if a worker is in danger. In mobile computing, a kill switch can disable a device that has been reported lost or stolen. By activating a kill switch, the network administrator can protect the data on the device from being stolen or altered. In a car or boat, a kill switch can prevent the vehicle from starting unless an associated security mechanism is activated.
Software programs sometimes include encoded kill switches as anti-piracy mechanisms. After installing the software, if a user fails to enter a valid registration key before a specified deadline passes, the software will either stop functioning or continue to function but with reduced capabilities. Microsoft Vista, for example, was designed to operate in "reduced function mode" if the user didn't register the software within 30 days.
Software-based kill switches (sometimes called virtual kill switches) are also often coded into platforms for smartphones and other devices as an anti-malware measure to protect the devices from infected apps. Microsoft, Google and Apple are among the companies that include kill switches in their products. When a problem is detected, the company can send instructions to the devices that will alter or remove the offending application.
Kill switches are also used for a wide variety of machinery both inside and outside the IT world, including car ignition systems, boat motors, industrial machines and gas pumps. A kill switch for vehicles and machinery is sometimes called a "dead man's switch" because its purpose is to shut the vehicle or machine down if the operator becomes incapacitated.
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