A process is a unique combination of machines, tools, methods and personnel engaged in providing a product or service. The output of a process can be product characteristic or process output parameter. Process capability indices (Cp, Cpk, Cpm) provide a common metric to evaluate and predict the performance of processes. In this study, at the first, the process capability indices are presented. Then machine capability indices are discussed. Finally, process performance indices Pp, Ppk, Ppm are presented.