Football, also known as soccer in some countries, has a set of rules defined by the International Football Association Board (IFAB). Here are some of the key rules:

1. The Field: A football field is rectangular, with dimensions typically around 100-130 meters in length and 64-75 meters in width. It’s marked with lines, including the goal lines and halfway line.
2. The Ball: The game is played with a spherical ball, usually made of leather or similar material.
3. The Teams: Each team consists of 11 players, including a goalkeeper.
4. Scoring: The objective is to score goals by getting the ball into the opponent’s goal. A goal is scored when the entire ball crosses the goal line between the goalposts and under the crossbar.
5. Offside: A player is in an offside position if they are nearer to the opponent’s goal line than both the ball and the second-to-last defender when the ball is played to them. Being in an offside position is not an offense in itself, but a player may be penalized if they become actively involved in the play from that position.
6. Fouls: Various types of fouls can occur, such as tripping, pushing, or handling the ball with the hands (except for the goalkeeper within their penalty area). The opposing team is awarded a free-kick or penalty kick depending on the severity and location of the foul.
7. Yellow and Red Cards: Referees can issue yellow cards as a warning for serious fouls and misconduct. A second yellow or a direct red card results in a player being sent off the field. A red card can also be issued for a particularly serious offense.
8. Throw-Ins, Corner Kicks, and Goal Kicks: When the ball goes out of bounds along the sidelines, the opposing team is awarded a throw-in. If the attacking team kicks the ball out over the goal line, the defending team gets a goal kick. If the defending team does this, the attacking team is awarded a corner kick.
9. Duration of the Game: A standard football match is played in two halves, each typically lasting 45 minutes, with a 15-minute halftime interval. In some cases, additional time may be added at the end of each half to compensate for stoppages.
10. Penalty Shootout: In knockout-stage matches that end in a draw, a penalty shootout may be used to determine the winner. Each team takes a series of penalty kicks to decide the match.

These are just some of the fundamental rules of football. The complete set of rules can be quite detailed and is maintained by the IFAB, which periodically updates them to ensure fairness and consistency in the game.