This article actually talks about Statistical Process Control (SPC), which is an industry-standard methodology for measuring and controlling quality during the manufacturing process. Quality data in the form of Product or Process measurements are obtained in real-time during manufacturing. This data is then plotted on a graph with pre-determined control limits. Control limits are determined by the capability of the process, whereas specification limits are determined by the client’s needs. Statistical Process Control also can be applied to any process where the “conforming product” output can be measured. Key tools used in SPC include control charts; a focus on continuous improvement; and the design of experiments.