Endometriosis is a chronic medical condition where tissue similar to the lining of the uterus (the endometrium) grows outside the uterus, often on the ovaries, fallopian tubes, or the tissue lining the pelvis. This abnormal growth can cause pain, especially during menstruation, as well as potential fertility problems. Symptoms include pelvic pain, heavy menstrual bleeding, pain during intercourse, and digestive issues. The exact cause is unknown, but it is thought to involve genetic, immune, and environmental factors. Treatment options include pain management, hormonal therapies, and in some cases, surgery.