The main objective in American football is simple: score more points than your opponent. Teams do this by moving a ball down a field and into a special area called the end zone. The game is a constant battle for territory.

There are two primary ways to score. The most valuable is a touchdown, worth six points. A touchdown happens when a player carries the ball into the opponent's end zone or catches a pass while inside it. After a touchdown, the scoring team can earn an extra point by kicking the ball through the opponent's goalposts.

The other main way to score is a field goal, worth three points. This also involves kicking the ball through the goalposts, but it's usually done when a team is close to the end zone but doesn't think they can score a touchdown.

A football field is a rectangle, 100 yards long from goal line to goal line. At each end of this 100-yard stretch is a 10-yard deep scoring area called an end zone. This is where touchdowns happen.

So, the total length of the field, including both end zones, is 120 yards. The field is marked with a line every five yards, and the numbers on the field count up from each end zone to the 50-yard line at the center. At the back of each end zone stand the goalposts, which look like giant tuning forks.

The game flows in a series of plays. The team with the ball, known as the offense, tries to advance it down the field. They have a set of four attempts, called downs, to move the ball at least 10 yards forward.

If the offense successfully gains 10 or more yards within their four downs, they earn a new set of four downs to try again. This is called getting a "first down." If they fail to gain 10 yards after four attempts, possession of the ball is turned over to the other team, which then gets its own chance to score.

Because of this rule, teams often use their fourth down to kick the ball. If they're close enough to the opponent's goalposts, they might attempt a field goal. If they are far away, they will typically punt the ball, kicking it as far downfield as possible so the other team has to start from a worse position.

A football game is divided into four 15-minute quarters, with a longer break called halftime between the second and third quarters. The clock doesn't run continuously; it stops for various reasons, like when a pass is incomplete, a player with the ball runs out of bounds, or a penalty is called. This is why a game that's technically 60 minutes of playtime can last for over three hours.

With these basics, you have the foundation to understand the flow of an American football game. It's all about gaining territory, managing your downs, and converting your progress into points.