Endocrinology is the study of hormones—chemical messengers produced by glands in the endocrine system—that regulate many physiological processes and behaviors. These hormones influence mood, stress responses, aggression, and social bonding. For example, cortisol is involved in the body’s response to stress, testosterone can affect aggression and dominance behaviors, and oxytocin promotes trust and bonding in social interactions. By examining how hormones fluctuate and interact with the brain, endocrinology offers insights into how our physiological states drive immediate reactions as well as long-term behavioral patterns.