The idea of quality control has been around a long time. A QC program involves certain accepted policies, methods and standards for the finished product. Many companies have QC departments and policies, but standards and methods are very different for different products and industries depending on expectations, traditions and current manufacturing trends.
So what is quality control and how should a company go about developing a QC program? A good place to start is with a definition of quality. D. Edward Demmings defined it as the "absence of variance." That seems reasonable, but there must be a standard in place and processes designed to achieve it. If a recognizable standard exists and processes have been developed to meet those standards, the only missing element is reliability. Reliability does come from control of variables. Another definition is "the expectations of your most demanding customers." If a company continually meets or exceeds customer expectations, they are doing pretty well. Add these two thoughts together and you have "systematic control of process variables to deliver goods that make customers happy."