The document is a literature review on efficient facial expression recognition (FER) methods, discussing various approaches and techniques in the field of computer vision. It highlights the significance of recognizing facial expressions for applications in human-computer interaction and other sectors, and examines methodologies like Gabor filters, Active Appearance Models, and Hidden Markov Models. The review also compares different FER methods, suggests future directions for improvement, and emphasizes the necessity for accurate facial expression identification systems.