Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus, causing inflammation, pain, and infertility. This condition affects approximately 1 in 10 women of reproductive age. Symptoms include painful periods, pelvic pain, and heavy menstrual bleeding. The exact cause is unknown, though hormonal and immune factors are implicated. Treatment options include hormonal therapies, pain management, and surgical removal of excess tissue. Early diagnosis can improve symptom management and fertility outcomes.