Depression is a common yet serious mood disorder that affects how individuals feel, think, and function. Clinically known as major depressive disorder (MDD), it is characterized by persistent sadness, loss of interest or pleasure in activities, fatigue, changes in appetite or sleep, feelings of worthlessness or guilt, and even suicidal thoughts. Depression can be triggered by genetic, biochemical, psychological, and environmental factors, and may be acute or chronic. It can impact all areas of life, including work, relationships, and physical health. Diagnosis is based on clinical assessment using tools like the DSM-5 criteria and validated screening instruments.

Treatment includes a combination of antidepressant medications, psychotherapy (especially cognitive-behavioral therapy), lifestyle changes, and in some cases, electroconvulsive therapy (ECT). Social support and early intervention greatly improve outcomes. Stigma remains a barrier to seeking help, but public education and advocacy have improved awareness and acceptance of depression as a treatable medical condition.