1. Learn a little history behind the offside rule. The offside rule originated in football's early days, in secondary school games; it was introduced to stop lazier players from simply hanging about the goal zone, waiting to take the ball and aim for an easy goal.^[2] Under the rules of Eton College (1847), being offside was once known as "sneaking".^[3] Over time, the offside rule has evolved to ensure a good balance of play (at one stage it was so tough that no goals were being scored!); by 1925 FIFA amended the rule so that only two players had to be between the attacker and the goal.^[4] In 1990, the rule was amended to help the game flow more freely again, through permitting an attacking player to be level with the second-to-last defending player without being called offside.^[5]
2. Understand what offside means. The reasoning behind the offside rule remains fairly much the same as when it was introduced, namely, it is aimed at preventing an attacking player from waiting for the ball close to the goal.^[6] In simple terms, being offside occurs when an attacking player goes behind the line of defenders before the ball has been kicked to them. In greater detail, being offside occurs when:
   • the attacking player is in the opponent's half of the field
   • the attacking player is closer to the end line than the second-to-last defensive player (including goal keeper) and the ball.
   • the attacking player is involved in the play, either by playing the ball or interfering with a defender or goalkeeper
   • When an offside is called, play is stopped and an indirect free kick (the ball must touch another player before a goal is scored) is awarded to the opposing team.
3. Work out whether the attacking player is actually in an offside position. Here is how to determine the offside position:
   • Keep an eye on the closest two defenders to the goal including the goalkeeper.
   • If there are fewer than two defenders (including the goalkeeper) between the attacking player and the goal, and the attacking player does not have possession of the ball, then the attacking player is in an offside position.
   • 

     Here, the blue forward to the left of this diagram is in an offside position
     If the attacking player is in an offside position and a teammate passes the player the ball or the player becomes involved in playing in any way, an offside should be called.
   • Note, however, that it isn't enough for a player to be in the "offside position" for it to be declared offside. The key element is "active play".
4. Understand what the referee does. The referee is in the position of calling an offside. Either the referee (linesman) or the referee's assistant, will raise his flag when he considers that a player is offside.
   • The assistant referee will raise his flag straight in the air to indicate there has been an offside infraction. The referee will make the call to stop play, or he can overrule the assistant referee.
   • The referee will indicate an indirect free kick is awarded to the opponent team by holding one arm in the air (before and after the restart) until the ball has touched another player on the pitch.
5. 

   Possession of the ball means no offside despite being in front of all but one defender
   Know when a player is not offside. When the ball is between a player and the goal, then the attacking player cannot be offside. Thus, the player can dribble the ball past the last defender.
   • A player cannot be offside on the defending half of the field. The furthest point that you must retreat to avoid an offside call is the halfway line.
   • A player cannot be offside directly from a throw-in.
   • A player cannot be offside directly from a corner-kick.
   • A player cannot be offside directly from a goal-kick.
   • The latter three points are easy to remember if you equate them with the ball leaving the field of play. The above three points are the restarts for the ball leaving play and therefore there is not offside on the following restart.
6. Note when offside ceases to apply. Offside only applies at the time that the ball was passed to the attacking player, not after the kick. Once a teammate passes a ball to the attacking player, he can legally sprint past the last defender to receive the kick because has possession of the ball.

Video

Tips

• The offside rule is subject to frequent revision - and such revisions can have major impacts on the way the game is played.^{[7] [8]}
• It is helpful to watch the offside rule in action. Two reliable sources are (you will need to choose your streaming option):
  • FIFA: http://www.fifa.com/worldfootball/lawsofthegame.html; and
  • Dynamic Thought: http://www.dynamic-thought.com/Offside.swf.
• The offside rule can apply to any player. It is not restricted to the forward line.
• The restart for an offside infraction (it is not a foul) is an indirect kick for the defending team.
• In some minor soccer games with younger kids, offsides may not be called by the referee.

Warnings

• Never argue with the referee, they will not reverse a call because you disagree. More likely you will just annoy them and they will be less likely to cut you slack later.

Related wikiHows

• How to Stop a Breakaway in Soccer As Goalie
• How to Understand Soccer Assistant Referee Signals
• How to Become a Professional Soccer Player
• How to Develop Good Soccer Dribbling Skills
• How to Do a Throw in Soccer

Sources and Citations

• The Offside Rule in Soccer - http://www.soccer-training-guide.com/offside-rule-in-soccer.html - research source
• Ask the ref, http://asktheref.com/ - a great source for referee call information - research source
• FIFA Rules of the Game - source of updated rules of football: http://www.fifa.com/worldfootball/lawsofthegame.html