What is the origin of curfew?

During the Middle Ages, houses in European towns were often made of wood and were close together, and fires could quickly spread from house to house. To prevent this, people were required to put out or cover their hearth fires by a certain time in the evening. A bell was rung as a signal when the time had come. In early French this signal was called coverfeu, a compound of covrir, meaning “to cover,” and feu, “fire.” Even when hearth fires were no longer regulated, many towns had other rules that called for the ringing of an evening bell, and this signal was still called coverfeu. A common coverfeu regulation required people to be off the streets by a given time. That was the meaning of the word when it was borrowed into Middle English as curfew.