Major depressive disorder (MDD) is a common and potentially destructive mood disorder characterized by symptoms like constant sadness, low self-esteem, and in extreme cases suicidal urges. Common triggers include abuse, loss, illness, genetics, and medication. Women are nearly twice as likely to experience depression due to their multiple social roles and responsibilities, hormonal changes, and life events like pregnancy and childbirth. Treatment options include psychotherapy, medication, exercise, yoga, meditation, and maintaining a healthy lifestyle. Seeing a doctor is recommended if symptoms persist more than six weeks.