Types of Seat belts
Most seatbelts must be buckled manually. This type of restraint is considered active. It requires action in order to be used. Passive restraints include seatbelts that automatically move to position when you enter a vehicle and airbags, since neither require action by the user.
If your vehicle was originally equipped with seatbelts, the law requires you to use them and that they are in good working condition. So, take the short moment or so to buckle your seatbelt and don't be passive when it comes to safety.