How to Play Football

The Field

Football, or soccer as it is sometimes know, is played on a field measuring 90 to 120 meters in length (100 to 110 m for international competition) and 45 to 90 meters in width (64 to 75 for international). At each end is centered a goal, consisting of vertical poles connected by a horizontal crossbar at their top. The insides of the poles (goal posts) are a distance of 7.32 meters, or 8 yards, apart, while the crossbar is 2.44 m or 8 feet from the ground.

The necessary pitch is actually quite simple: the field is painted or otherwise marked with lines up to 12 cm thick. Below are the standard lines for a soccer field, with the required lines in bold:
the two shorter boundary lines, known as goal lines
the two longer boundary lines, known as touch lines
a halfway line
a center mark, with...
a circle of radius 9.15 m = 10 yards around it
a goal area, also known as a six, around each goal, consisting of a box bounded by two 6-yard lines drawn perpendicularly from the goal line 6 yards (5.5 m) from each goal post, and the horizontal line connecting them.
a penalty area, around each goal area, consisting of a box bounded by two 18-yard lines drawn perpendicularly from the goal line 18 (16.5 m) from each goal post, and the horizontal line connecting them.
a penalty mark located 12 yards (=11 m) perpendicularly from the center of the goal. This can be scraped into the field by the referree, if necessary
a penalty arc, consisting of the portion of a 10-meter-in-radius circle about the penalty mark that lies outside the penalty area
a corner arc, or quarter circle of radius 1 yard, drawn in each corner of the field.

Equipment

Ideally, all the above lines are on the field, and it is of appropriate dimensions. In addition, however, certain equipment is necessary.

The goals must be anchored to the ground properly, so as to withstand the impacts of players and balls striking them.
Each goal must be equipped with a net, secured to the crossbar and goal posts. This is merely to help the referree determine when a ball crossing the goal line is a goal, and when it is out of bounds.
Positioned in each corner should be corner flags, each of at least 5 feet in height.
The ball must be spherical, made of suitable material, inflated to a pressure of .6-1.1 atmospheres (8.5 - 15.6 lb/sq. in.), of 68-70 cm in circumference, and of 410 - 450 grams in weight at the start of the match. Should the ball burst or otherwise become defective during the match, a new ball should be obtained and restarted by a drop ball (see Restarting Play) at the point where the ball became defective.

In addition to the field, each player should have certain equipment. Players should wear cleats, or shoes with spikes on the soles, prefereably made of plastic and not metal. For protection, mouthguards and shinguards are also recommended.

The Teams

Each team consists of 11 players, one of which is a goalkeeper. A minimum of seven players are required for each team in order for the match to begin. In official competition, each team is limitted to three designated substitutes.

The standard positions are forwards, consisting of wings and strikers, midfields, and defenders, consisting of wings, stoppers and/or sweepers, plus a keeper. The 10 non-keepers are split up among the positions according to the coach's discretion.

The Match

The regulation soccer match is 90 minutes in length, consisting of two forty-five minute halves. Between the halves is a halftime of approximately five minutes.

In competition play, when the score is tied after regulation time is up, several steps are taken. First, stoppage time is added, obstensibly to make up for the several minutes of time taken up between plays. After this, two five-minute overtime periods are conducted, after which the teams begin a Penalty Shootout. Should all this fail to break the tie, the teams begin a short Sudden Death period, after which the game is declared an official draw.

Stoppage of Play

Play stops when one of the following occurs:

A goal is scored
The ball goes out of bounds, but a goal is not scored
An infraction occurs
The ball becomes defective
A player is injured

Substitutions

A team may substitute one of their extra players for a player on the field when...
...that player is injured and needs to be replaced
...that team is taking a throw-in
...either team is taking a goal kick

Each team may make two such substitutions per half, although since there are only three subs and players may not reenter the game once substituted, a team may not use all four opportunities. The exception is substitution for injuries, which is free for that team. However, the ref must give the other team a free substitution at the same time, if that team desires it.

Restarting Play

Play is restarted after a stoppage in one of several ways. When a new half begins, or a goal is scored, play restarts with a kickoff. At the beginning of the match one team is randomly chosen to kick off, while the other will do so in the second half. When a goal is scored, the team on which it was scored takes the kickoff. A kickoff consists of one player on the kicking team moving the ball forward on the referree's signal. Until this, the opposing team may not enter the center circle. After the ball has been moved forward, however, it is fair game.

The Second restart is the throw-in, which occurs when one team propels the ball across a touch line. The other team selects a player to throw the ball in bounds. This must be done with two hands on the ball, with the ball thrown over the thrower's head. In addition, at the time the ball is released, both of the thrower's feet must be on the ground.

Another restart is the goal kick, occuring when a team propels the ball across the opposing goal line, but does not score a goal. One player on the other team positions the ball anywhere within the goal area and kicks it. The only limitation is that it must leave the penalty area before it is played.

When a team propels the ball across their own goal line, the other team restarts the ball with a corner kick in the corner closest to where the ball left play. The team taking the kick places the ball anywhere within the appropriate corner arc and kicks it. This is often a prime goal-scoring opportunity for the kicking team.

The remaining restarts occur only after a player commits an infraction, and vary depending on the severity. For minor infringements of the Laws of the Game, the ball is restarted with an Indirect Free Kick. Examples of such infractions are Offsides, passing to the keeper, dangerous play, and more. In these cases, a free kick is taken by the opposing team from the location of the offense, but this kick may not result in a goal before it is touched by another player. For more serious offenses, committed in a manner deemed to be careless, reckless, or using excessive force, a Direct Free Kick is issued. Examples include handballs and pushing, tripping, or charging an opponent. A Direct Free Kick is taken from the location of the infraction, unless it occurs within the opponent's goal area, in which case it is taken from the six-yard line. In this case, the kicking team is allowed to score on the initial kick.

Finally, when a team commits an offense within their own penalty area, their opponents are rewarded a penalty kick. This is taken from the penalty mark, and only the kicker and the keeper may be in the penalty area until the ball is kicked. In addition, all players must be 10 yards away from the kickers, which is to say, outside the penalty arc. While the kicker shoots, the keeper may not leave the goal line, and must therefore commit to diving either one way or the other. If he or she guesses correctly, he has a chance of blocking the shot, while if not, it is almost certainly a goal.

Offsides

Offsides is one of the most difficult rules of soccer for a non-player to understand, because it requires an instinct for the locations of players on the field. Basically, a player is in an offsides position when he or she is beyond the offsides line, determined by the ball, the halfway line, or the second-last defender, whichever is closest to the defenders' goal. This in itself is not an infraction. However, the defending team is awarded an Indirect Free Kick for an Offsides Violation whenever an attacking player derives strategic benefit from being in an offsides position. This usually takes the form of receiving a pass which was sent while the player was in an offsides position, although other situations arise quite often. However, if you are in an onsides position when a ball is kicked but run to an offsides position to receive it, there is no violation! Thus, Offsides is a very difficult rule to call, and linesmen are often employed to assist the ref in this area.

Infractions

When a player breaks the Laws of the Game, the Referree takes certain action depending on the severity of the offense. Most offenses merely receive verbal warning. However, a player may be officially Cautioned and shown a Yellow Card for...
...dissent
...persistent infringement
...unsporting conduct
...delay of game
...failure to respect and acknowledge the referree
...and MORE!

When a player commits a second Cautionable Offense, that is, after he has already been shown a Yellow Card, or when he or she commits a Sending-Off Offsense, he or she is ejected from the game and shown a Red Card. Sending-Off offenses include...
...serious foul play
...spitting
...swearing
...denying an obvious goal-scoring opportunity by breaking the Laws of the Game
...violent conduct...
...and more

When a player is sent off, his team must play with one fewer players for the remainder of the match.

Officials

To enforce the Laws of the Game, each match is officiated by a referree. This official is usually equipped with a whistle with which to stop play, and is generally given complete power over the players and coaches involved in the match. To Assist the ref, there are generally appointed two linesmen who make out-of-bounds calls and Offsides calls. In addition, some matches have a Fourth official to further help the ref.

Final Thoughts

It is impossible for one writeup to do justice the entire game of Soccer/Football. However, hopefully this has introduced you to the basic rules and regulations of the sport.

Source:
FIFA's (Federation Internationale de Football Association) Laws of the Game, available online at http://www.fifa.com/handbook/laws/2002/LOTG2002_E.pdf.