Myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular junction characterized by fluctuating skeletal muscle weakness. This comprehensive chapter provides an in-depth review of the epidemiology, immunopathogenesis, clinical spectrum, diagnostic strategies, and evolving treatment landscape of MG. Emphasis is placed on the role of pathogenic antibodies—anti-AChR, MuSK, LRP4, and agrin—and their diverse clinical phenotypes. We outline the diagnostic approach, including serologic, electrodiagnostic, and imaging tools, and highlight critical bedside signs such as Cogan’s lid twitch and the ice pack test. Treatment strategies are detailed across disease stages and subtypes, including symptomatic agents, immunosuppressants, thymectomy, rescue therapies, and advanced biologics like complement and FcRn inhibitors. Special considerations for pregnancy, pediatric, and elderly patients are addressed, as are current research trends and future therapeutic directions. Through case-based illustrations, this chapter integrates real-world application with expert consensus to provide a practical, scholarly resource for clinicians managing MG.