Gridiron football is an umbrella term used in some countries outside North America to refer to several codes of football played primarily in Northern America. The term refers to the sport's characteristic field of play, which is marked with a series of parallel lines resembling a gridiron.
Gridiron football is distinguished from other football codes by its use of heavy protective equipment, the forward pass, the system of downs, a line of scrimmage, distinct positions and formations, and the ability to score points while not in possession of the ball (by way of the safety). Walter Camp is credited with creating many of the rules that differentiate gridiron football from its older counterparts. The game descends from rugby football, itself an umbrella term for various similar codes (union, league and sevens).
According to certain early rules of American football, some fields were painted with square-like "grids" of demarcation. The ball would be snapped in the grid in which it was downed on the previous play. This was abandoned in favor of the system of yard lines and hash marks now used. An example of a field that was painted with such a grid pattern is the old Archbold Stadium at Syracuse University, which has since been torn down.
The word gridiron alone may refer either to the field or to the sport; however, in North America it is mostly used in reference to the field, usually in a somewhat figurative or poetic sense. In some other English-speaking countries—particularly Australia and New Zealand—it is the primary term used to refer to the sport, differentiating it from other forms of football such as Australian football, association football (soccer), rugby league, and rugby union. In the United Kingdom the most frequently used term is American football, but gridiron is also used to describe the game.