A four-step buttonhole is a feature on sewing machines that allows a buttonhole to be created in four separate, successive steps. The user successively selects the individual sewing phases, usually using a rotary dial. The machine first sews one side of the buttonhole, then a bar tack, subsequently the second side of the buttonhole, and finally the second bar tack to complete it. After each step, it is necessary to stop and manually switch to the next phase. This method of sewing buttonholes is typical for mechanical and older models of sewing machines.