Process control is a discipline that deals with maintaining the output of an industrial process within a desired range. It enables automation and mass production with small staff. For example, controlling room temperature involves measuring the temperature (input), comparing it to the desired setpoint, and adjusting the heating source (output) to keep it constant. Larger systems can be controlled by distributed or supervisory control and data acquisition systems. Process control includes discrete, batch, continuous, and hybrid applications in various industries like oil refining, chemicals, and power plants. Statistical process control uses charts to monitor process variation and detect quality issues.