Gravity is a program to simulate the path of move for bodies (i.e. objects with mass) altered by the gravity drive between each other, i.e. a gravity simulator. As a fundamental physical phenomenon, gravity is on curriculum at elementary and secondary schools and at vocational higher schools, thus it is an aid for both pupils and teachers, when they can see orbital paths in addition to imaging them. Sitting before the computer, a process that lasts effectively for years may take place in a few seconds, the Kepler's and Newton's law are understood in a shorter time.