Depression is clinically classified as a mental illness, specifically a type of mood disorder. Its main clinical manifestations include low mood, slow thought processes, reduced volitional activity, fatigue, lack of interest, lack of pleasure, often accompanied by sleep disturbances, changes in weight, changes in sexual desire, and low self-esteem. Patients often feel fatigued and dissatisfied throughout the day, and their attention may decline. They may experience feelings of guilt, worthlessness, futility, and despair. It is not uncommon for patients to have thoughts or behaviors of self-harm or suicide. Thus, depression is a mental disorder that requires systematic antidepressant treatment once diagnosed. Effective treatment outcomes can often be achieved through a combination of medication, psychotherapy, and physiotherapy.