Football is a team sport in which players try to advance a cowhide-covered ball over an opposing team’s goal line into their end zone for a score. The game’s basic structural elements include kickoffs and downs. Players must follow a set of rules to avoid penalties that move the ball away from where it should be or towards their opponent’s end zone.
After the coin toss, the starting team gets four downs to advance the ball at least 10 yards. If they fail to do so, the other team takes over possession from where they stopped on their last play. If the team successfully crosses midfield, they get another four downs and can start over at their original 5-yard line.
The field has stripes running the width of the field and shorter lines, called hash marks, that mark each single yard interval down the field. Teams are allowed a maximum of 11 players. Each player must wear protective gear that includes a helmet, padded shoulder pads, and thigh and chest protectors.
Each team has a defensive and offensive unit, and special teams that handle punts and kickoffs. There are also referees to supervise the game and enforce its rules. Each player must abide by certain rules, including not touching the ball with hands or arms. Whenever a player violates a rule, an official throws a yellow flag to signal it. A penalty usually moves the ball away from the defense’s end zone in the case of a defensive violation or towards the offense’s end zone in the case of an offensive one.
The most common way to advance the ball is on a running play, in which the ball-carrier carries the ball. However, players may also use short passing plays to circumvent a tough ground defense. In both cases, the goal is to get the ball over an opposing team’s goal-line into their end zone for a touchdown.
The ball-carrier can only lose the ball if it fumbles, steps out of bounds, is tackled behind the line of scrimmage, or a tripping penalty is committed. If the ball is fumbled and a player recovers it, he can run with the ball until tackled or forced out of bounds. Losing the ball in this way is a turnover. Other turnovers occur when a forward pass is intercepted or if a fumble is recovered by the other team. These turnovers give the other team a chance to try for a touchdown.
