Derived from the English game of rugby, American football was started in 1879 with rules instituted by Walter Camp, player and coach at Yale University.  In 1888 tackling as low as the knee was permitted.  From 1876 through 1879, the game was rugby, with only a few minor American embellishments. But during the next four years (1880-1883), all this would change.  Walter Camp contributed some of the changes from Rugby and Soccer to American football.  The first thing that Walter Camp changed was that one side retained undisputed possession of the ball, until that side gives up the ball as a result of its own violations.  Walter also changed the line of scrimmage, and 11 players on a team instead of 15.  Camp created the quarter-back and center positions, forward pass, standardized the scoring system, numerical scoring and the safety, interference, penalties, and the neutral zone for football.  A touchdown increased in value to six points and field goals went down to three points in 1912.