Curfew is important because is respectful of the responsible party’s time. For example, if a curfew is set by your parent or guardian, it is respectful to the them to be home by it. Otherwise, they are left worrying about you and left to decide if they should start an emergency search for you, etc. If a curfew is set by city officials, it is important because it allows law enforcement officials the ability to know right off that someone out after curfew is most likely causing trouble. It would also allow the city quiet time, in which residential folks could count on being able to sleep without noisy cars, yelling or other disruptive behavior.