American football
American football, known in the United States simply as football, and in some other English-speaking countries as gridiron football, is a team contact sport that emerged from a variation of rugby and that rewards speed, agility, tactical ability and brute strength of the players who push, block and chase each other, trying to advance a ball into enemy territory during an hour of playing time, which becomes three or four of real time. American football is often seen as a metaphor for war, with a lot of personal violence and elaborate strategies taking place on the field, with heavy and strong players pushing each other with every ounce of their weight, and with a defined front line , which moves back and forth along the field, separating the attack and defense teams.
Source: Wikipedia