This document discusses endometriosis, including its definition, theories of pathogenesis, risk factors, clinical presentation, investigations, staging, and management approaches. It provides an overview of endometriosis, describing it as the presence of functioning endometrial tissue outside the uterine cavity, with a reported incidence of 20-25% in the reproductive age group. Theories discussed to explain its pathogenesis include retrograde menstruation, coelomic metaplasia, and metastasis. Hormonal factors, immunology, and genetics are also implicated in its development. Staging is typically done using the revised American Fertility Society classification system. Management involves a tailored approach considering symptoms, fertility goals, and side effects of treatments.