When the type of tissue that lines the uterus starts growing outside the uterus as well the medical condition is known as Endometriosis. It is a chronic disease. What does a chronic disease mean? It is a long-lasting condition that cannot be cured but can be controlled. Endometrium is the name of the tissue that lines the inside of the uterus. Implants (the clumps of tissue) in this condition grow on the ovaries, fallopian tubes, the outer wall of uterus, the intestines and other organs in the belly. In certain cases it exceeds and spreads to areas beyond the belly. In every menstrual cycle the implants also how, breakdown and bleed same as it happens inside the uterus in the uterine lining. The menstrual build is discharged from the body during menstruation but the misplaced tissue has no place to go thus leading to inflammation and swelling. The inflammation produces scar tissue around the area of endometriosis. These endometrial tissue sites may develop into lesions, implants, nodules or growths. It is also a prime cause of failure to conceive in certain cases. The pain and discomfort associated with endometriosis starts a few days before the menstrual period and is usually gone by the time menstruation end. In case where the implants grow in some sensitive area it can cause severe pain during sex, exercise and bowel movements.