Football is a game played on a field that is 120 yards long. The "playing" part of the field is 100 yards, and there are two end zones that are ten yards long each. The end zones are where the goal posts that are used for extra points and field goals are located.
The player on offense can either run while carrying the football or throw it (called passing) over the defense to a player on his team. If a player carries the football over the goal line at the end of the playing field without being tackled, he has scored a touchdown. A touchdown is worth six points, and if the extra point after the touchdown is good, it is worth one more point.
A field goal is similar to the extra point, but the field goal can be attempted instead of trying for a touchdown. It is worth three points. The kicker has to kick the football between two goal posts that are located behind the goal line.
The team with the football is called the offense. They have four downs to move the ball ten yards toward the goal line of the defense. An incomplete pass costs one down. Also when a play ends in a tackle of a runner, it counts as one down. If the offense reaches the fourth down and has still not advanced ten yards toward the defense's goal line, then it usually punts the football. After the punter kicks the ball, the receiver on the other team can either call a "fair catch," run with the football until tackled, goes out of bounds, or makes a touchdown. A "fair catch" is called if there are several members on the other team surrounding the receiver making it hard for him to have a chance to run with it.
One thing that the team with the football (offense) does not want is for it to be third down and long. This means the team must make several more yards than the usual ten yards for a first down because they have been tackled behind their "line of scrimmage." In other words, where they were on the playing field on the first down. This is especially important to avoid in the National Football League because it has some very good players. Many times the team tries to pass it far enough for a first down, but it is often intercepted. A run with the football can take the defense by surprise, but the offensive player will usually not gain enough yards for a first down. Since a punt on the fourth down happens several times in a game, the best plan might be to have a player try to run for a first down on the third down and long and then punt if he does not make the first down.
In college football games, they sometimes punt on the third down in similar situations. If a pass is intercepted, then the player that made the interception can run the ball until he is tackled or runs out of bounds. Often the player runs all the way for a touchdown or at least to field goal range. Although a field goal can be blocked, it is usually either good or no good. The distance the football must be kicked to make it between the goal posts plays an important part as to whether it will be good or not. If the distance is about fifteen yards or twenty yards, then it will probably be good. If the distance is forty yards or more, it will probably be no good.
Another thing that the offense does not want to happen is a fumble of the football. A fumble happens if the player carrying the football drops it onto the ground. If this happens, then any player including the player that was carrying the football can recover the football by either picking it up and running with it or falling on it and holding onto it. Any defensive player can knock the football out of the hands of the other team player who is carrying the football.