Endometriosis is a complex, systemic inflammatory condition where tissue similar to the uterine lining grows outside the uterus, causing pain, inflammation, adhesions, and a wide range of symptoms. Affecting 1 in 10 women, endometriosis is often misunderstood, underdiagnosed, and frequently dismissed, leading to delays in diagnosis and treatment. This guide breaks down what endometriosis is, where lesions form, why it’s not just a gynecological disease, common symptoms, staging systems, possible causes, and how it’s diagnosed and treated. If you’re navigating chronic pelvic pain, painful periods, bowel or bladder symptoms, infertility, or unexplained fatigue, understanding endometriosis is an essential step toward receiving proper care and advocating for yourself.