Door security is the use of physical or electronic devices to prevent unauthorised access to premises by intruders. These include locks, locksets, bolts and deadbolts. Door security consists of a wide range of measures designed to strengthen doors and protect premises from the extremes of weather, fire and crime. They include door threshold guards, door-open detectors, smoke alarms and burglar alarms. Door security is used in commercial and government buildings, as well as in residential settings.