Depression is a common but serious mental health disorder characterized by persistent feelings of sadness, hopelessness, and a lack of interest or pleasure in daily activities. It can also affect a person's energy levels, sleep patterns, appetite, concentration, and overall ability to function. Depression varies in severity and duration and may be caused by a combination of genetic, biological, environmental, and psychological factors. With proper treatment, including therapy, medication, or a combination of both, individuals can manage symptoms and improve their quality of life.