SPC stands for Statistical Process Control. It is a methodology used in quality control to monitor and control a manufacturing or production process. SPC involves the use of statistical techniques to analyze process data and make informed decisions to ensure that the process operates efficiently and consistently, producing products of high quality.

The main objective of SPC is to identify and eliminate or reduce variations in a process that can lead to defects or non-conformance with specifications. By monitoring and analyzing process data, SPC helps in identifying any special causes of variation that need to be addressed.

SPC typically involves the following steps:

1. Data Collection: Process data is collected at regular intervals from the manufacturing or production process. This data can include measurements of key process parameters, such as temperature, pressure, or dimensions.

2. Data Analysis: The collected data is analyzed using statistical techniques to determine the process's current performance and identify any trends or patterns. Control charts are commonly used in SPC to visually represent the data and detect any out-of-control conditions.

3. Process Monitoring: Control charts are used to monitor the process over time and identify any points that fall outside the control limits or exhibit unusual patterns. These points are known as "out-of-control" signals and indicate the presence of special causes of variation that need to be investigated and addressed.

4. Process Adjustment: When an out-of-control signal is detected, appropriate corrective actions are taken to eliminate the special cause of variation. This may involve making adjustments to the process settings, equipment calibration, or other factors that contribute to the observed deviation.

5. Process Improvement: SPC also focuses on continuous improvement. By monitoring the process and analyzing the data over time, insights can be gained into the sources of variation and opportunities for process optimization. This information can be used to implement long-term improvements to enhance the overall quality and efficiency of the process.

SPC is widely used in industries such as manufacturing, automotive, electronics, pharmaceuticals, and many others. It helps organizations maintain control over their processes, reduce waste, and improve customer satisfaction by ensuring consistent quality in their products or services.