Human interaction is characterized by how we perceive each other, and our perception is decisively determined by the consciously and unconsciously emitted signals. Body odor is one signal that provides information about the other person – from eating habits, age, menstrual cycle, or inflammation status to current emotionality. This talk sheds light on the olfactory communication between sender and receiver, delineates how body odors change over the life span, which acute stresses are reflected in body odors, and how this changes the chemical composition of the odor-active volatiles.