Nice, concise answer from Wikipedia: A Kegel exercise, named after Dr. Arnold Kegel, is one designed to exercise the pubococcygeal muscles. These muscles are sometimes called the "Kegel muscles" in reference to the exercise. The aim of Kegel exercises is to restore muscle tone and strength to the pubococcygeal muscles in order to prevent or reduce pelvic floor problems. Kegel exercises are said to be good for helping to prevent vaginal prolapse in women, and urinary incontinence in both men and women. Kegel exercises are also known as pelvic floor exercises, or simply Kegels. Factors such as Pregnancy, childbirth, and being overweight often result in the weakening of pelvic muscles. Kegel exercises are useful in regaining pelvic floor muscle strength in such cases. Kegel exercise can also increase sexual pleasure for females and their partners. To isolate and identify the muscles involved, one can practice stopping the flow of urine while urinating. Once a person has identified the muscles involved, he or she can later exercise them at his or her leisure by consciously contracting them. http://en.wikipedia.org/wiki/Kegel_exercise