Cpk, or Process Capability Index, is a statistical measure used to assess how well a process can produce output within specified limits. It compares the width of the process variation to the width of the specification limits, indicating how capable a process is of meeting quality standards. A higher Cpk value suggests a more capable process, while a lower value indicates potential issues in meeting specifications. To calculate Cpk, the formula considers both the mean and the standard deviation of the process. It helps organizations identify areas for improvement and ensure that products consistently meet customer requirements, ultimately enhancing overall quality and efficiency.