Hemophilia is an inherited disorder in which the blood does not clot normally because there is a lack of certain clotting factors. There are two main types of hemophilia: hemophilia A (the most common type) and hemophilia B. While hemophilia usually occurs only in males, there are rare exceptions in which a female will have the blood disorder. Symptoms of hemophilia include bleeding (which may occur internally in joints and muscles) and bruising. Treatment for hemophilia most often involves replacement therapy, in which the clotting factor missing in people with the disease.