A process is broadly defined as an operation that uses resources to transform inputs into outputs. It is the resource that provides the energy into the process for the transformation to occur. Process control is the act of controlling a final control element to change the manipulated variable to maintain the process variable at a desired Set Point. Controlling a process requires knowledge of four basic elements, the process itself, the sensor that measures the process value, the final control element that changes the manipulated variable, and the controller.