Facial Action Coding System (FACS)

The Facial Action Coding System (FACS) is a comprehensive tool for understanding human facial expressions. Developed by Paul Ekman and Wallace V. Friesen, FACS categorizes facial movements into specific units, called Action Units (AUs). Each AU corresponds to the contraction of particular facial muscles, allowing researchers and professionals to decode emotions like happiness, sadness, anger, and surprise. FACS is widely used in psychology, animation, and security to analyze and interpret nonverbal communication, enhancing our understanding of human emotions and social interactions.