Ekman and Friesen's Facial Action Coding System

Ekman and Friesen's Facial Action Coding System (FACS) is a scientific tool used to categorize every facial movement caused by muscle activity. It breaks down expressions into small units called Action Units, which correspond to specific muscles. By analyzing these units, experts can identify emotions like happiness, anger, or surprise with high accuracy. FACS is used in psychology, security, and research to understand how and why people express feelings through their faces, providing a standardized way to interpret facial signals objectively and consistently.