Football is a team sport in which players compete to move a ball into the opposing team’s end zone. The game has two teams, with each having 11 to 18 players on a field that is typically rectangular in shape. Football is the most popular sport in many countries of Europe and South America. It also is widely played in the United States, where it is known as American football.
Modern football evolved from medieval “folk” games, which were usually played in villages according to local custom and lacked written rules. These often were violent, destructive, and chaotic affairs — and they were considered lower in status than more “gentlemanly” endeavors, such as equestrian sports. With industrialization and urbanization, these folk games declined in popularity from the early 19th century onward.
In the late 1890s, a few schools began to organize football clubs and play against one another. As these clubs grew, they gradually became more organized and formalized their playing rules.
The most basic element of football is the playing field, which is a large rectangular area marked by two goal posts at each end of the field. The field is divided into a number of sections called quarters by lines running diagonally across the width of the field. Each quarter is played in turn by each team. At the end of each quarter, the team that has the ball first gains possession by crossing the opponent’s goal line.
On most plays, an offensive team has seven players on the line of scrimmage. These players are known as the offensive line. They block for the running backs and wide receivers, protecting them from defenders while creating openings for them to gain yards. A team may vary the number of tight ends, wide receivers and running backs it uses on any particular play.
Players on the defensive side of the football field try to stop the offensive players from gaining yards and prevent passing completions. The defensive backs line up next to the defensive line and cover the receivers. In some formations, the linebackers may rush the quarterback or defend against a pass. The defensive backs and linebackers are the backbone of any successful defense.
If a forward pass is incomplete (flies out of bounds or touches the ground before being caught), the officials blow a whistle to signal that the team’s play has ended. The official then gives the ball to the team that was originally on offense for a new series of plays. The team must gain a first down by advancing the ball at least 10 yards in four downs.
In addition, the team must avoid committing any fouls, which are violations of the rules. Some of these result in the penalized player having to return a kickoff or punt. Other penalties can cause the ball to be moved forward, backward or out of bounds, or result in the opposing team being awarded a free kick.