A curfew is an order specifying a time during which certain regulations apply. Typically it refers to the time when individuals are required to return to and stay in their houses or homes. Such an order may be issued by public authorities but also by the owner of a house to those living in the household. For instance, an au pair is typically given a curfew, which regulates when they must return to the host family's home in the evening.
Curfews are a common element of control used in Martial Law though curfews can also be implemented for public safety in the event of a disaster or crisis.