Football, a term encompassing various sports, primarily refers to American football, a popular team sport that evolved from rugby in the nineteenth century. In American football, two teams of eleven players aim to advance a ball across a rectangular field to score points. The game has seen a high degree of specialization among players, leading to frequent substitutions during play. Alongside American football, the term "football" also applies to other sports like Canadian football, Australian rules football, association football (soccer), and rugby football, all of which involve teams trying to move a ball to score points. The name "football" originates from the fact that these games are played on foot, as opposed to horseback. For those interested in delving deeper, there are numerous Research Starter articles available that cover various aspects of football, including its history, notable leagues like the NFL and CFL, and significant events such as the Super Bowl. This topic offers a rich exploration of sports culture, strategies, and the evolution of gameplay across different regions and styles.