Body posture refers to the positioning of a person's body and can provide information about their attitude. Facial expressions like face touching, mouth covering, and fake smiling can indicate deception, while crossed arms can signal defensiveness but can also help with concentration. Good sitting posture involves feet flat on the floor and a straight but relaxed back, while good standing posture has a slight bend in the knees. Leg positions like parallel, apart, forward, and crossed can also reveal information about a person's confidence and familiarity. Maintaining good posture is important for spine health and blood flow.