Pay grades facilitate the employment process by providing a fixed framework of salary ranges, as opposed to a free negotiation. Typically, pay grades encompass two dimensions: a "vertical" range where each level corresponds to the responsibility of, and requirements needed for a certain position; and a "horizontal" range within this scale to allow for monetary incentives rewarding the employee's quality of performance or length of service. Thus, an employee progresses within the horizontal and vertical ranges upon achieving positive appraisal on a regular basis.