Why is there American football?

Answer 1

The first American colleges that played what they called football each had their own set of rules. That made it hard for the schools to play against each other, so they eventually sat down and drew up a standardized set of rules, based on the English Rugby code. Over the years, rules were adjusted and changed, and the game slowly evolved away from its rugby roots and into its own sport.

Walter Camp was responsible for developing many of the rules that set American football on its own path, including a down-and-distance system, a scoring system, and the establishment of a line of scrimmage in place of the rugby scrum. When the forward pass was legalized in the early 20th century, American football became a truly distinct game from rugby.