Automatic elevators are elevators that runs automatically without having passengers to press floor buttons. They can either be a traction or hydraulic model.
Automatic elevators runs without having floor buttons pressed. When passenger enters and/or leaves the elevator cab, door sensors detects passengers as they enters and/or leaves. After the doors closed, the elevator will starts to run by it's own, then stopping on each floors (when there are more than two floors). Inside the cab there are no floor buttons except alarm and door control buttons.
After the last passenger leaves the cab, the elevator will continue to run until on the next floor, then it will parks itselves and stays there until the next passenger use it.
A similar mode is Sabbath service. This mode works similarly to automatic elevators in which presing any floor buttons is not required. The elevator will instead run to each floor sequentially in one direction; once it reaches a terminus floor, it reverses and stops all floors in the opposite direction.