Middle school, also known as Junior High school, is a school in the secondary educational system that usually bridges the gap between elementary and high school. The exact organization varies, but most often middle schools consist of sixth, seventh, and eighth grades, students usually being between the ages of 12-14. Junior high schools traditionally include only seventh and eighth grades. The middle school is most common in the United States. Variations of middle schools exist in education systems around the world, although in some countries there is no designated school that bridges between elementary and high school.