Football is a sport played by two teams of 11 players on a rectangular field. The offense tries to get the ball into the other team’s end zone for points, while the defense tries to stop the offense from doing so.
The game begins with a coin toss that decides which team will receive the first kickoff. After a kickoff, each team battles for possession of the ball by running and passing the ball. A team may also recover a fumble or pick up an intercepted pass.
A player can advance the ball only if he or she has moved ten yards past the line of scrimmage (the imaginary line that runs across the field). Yardage markers are placed at 10-yard intervals, and teams must get to these marks before they can complete a play.
Each team has a set of rules that govern the way they play the game. These rules vary slightly by league, but a few key principles are generally shared.
During each play, the officials count the number of yards that each team advances and then place the ball at the spot where it ended. This is called a “first down” and the team that gained this yardage is then the ball carrier for that play.
After each play, the officials also determine how many yards a team has lost. This is done by measuring how far a team was tackled behind the line of scrimmage.
A team that is ahead on the scoreboard can try to make up lost yards with a series of short passing plays called “quarterback passes.” These are sometimes used by an offensive quarterback, but can also be thrown to running backs who can carry them for a few additional yards.
These passing plays are sometimes combined with a series of quick running plays called “huddles.” The most common goal for a team is to gain a touchdown, which occurs when the ball crosses the opposing team’s goal line. A team can then attempt to add one or more points with a series of extra-point conversion attempts, which are similar to field goals in rugby.
The field of play is 100 yards long with a 10 yards-long end zone for each team. The end zones are marked with stripes and haveh marks that mark ten-yard intervals down the field.
In a standard adult game, each team plays four quarters of 15 minutes each and an extended halftime break in between. After the fourth quarter, if the scores are tied, the game goes into overtime.
If a team fails to score in the extra time, the game ends. In the NFL, teams are awarded extra points if they are able to complete a touchdown or score a safety.
A safety is a rare occurrence in which an offensive ballcarrier is tackled, forced out of bounds or commits certain penalties within his own end zone. A safety is worth 2 points, and this score is usually scored by the defense when an offensive ballcarrier is tackled or forced out of the end zone.