To many Americans, autumn is more than just a time for raking leaves -- it's football season.

American football originated in the early 1880s at Yale and other U.S. colleges. It gradually evolved from the game of rugby, which itself was derived from association football, known as soccer by Americans.

American football is remarkably different from soccer, which is what the rest of the world calls "football." Soccer players use their feet to kick the ball toward the goal and are not allowed to touch the ball with their hands. American football players, on the other hand, spend a great deal of time carrying or throwing the ball, rather than kicking it.

The ball used for football was originally spherical like a soccer ball, but it is now pointed at two ends, allowing it to be thrown long distances. An American football is often called a "pigskin," supposedly because early games were played using an inflated pig bladder!

American football is played on a 100-yard playing field, divided by a 50-yard line. Other lines mark increments of one, five, and 10 yards. A football field is often called a "gridiron" because these various markings make the field resemble a cooking grille.

The object of the game is to advance the ball into the opponent's end zone (a touchdown, worth six points) or to get close enough to kick the ball through the goal posts located behind the end zone (a field goal, worth three points). Extra points are also awarded if the team successfully completes a supplemental scoring play after a touchdown. Points can also be earned by the defense for tackling an opponent in their own end zone. Football games typically consist of four 15-minute quarters, but thanks to frequent clock stoppages and time outs, they can easily last three hours or more.

Because of the sport's rough nature, women generally do not play football. However, football has many faithful female fans among its vast following. In one recent survey of the top 125 most popular sports among Americans, football occupied three of the top 10 spots on the list (professional football was 1st, college football was 9th, and high school football was 10th).

Every fall, weekly football games are played at high schools, colleges, and professional stadiums around the country. High school championships are generally played in November, while college football championship games are played around New Year's Day. The National Football League championship, known as the Super Bowl, is played in late January and is the world's most-watched live sporting event, with a global television audience of 1 billion in over 150 countries.

By Jeff Richards