Main Soccer Rules
The official soccer rules are called the "Laws of the Game" and are revised annually (usually in July) by FIFA, the world soccer governing body, but youth organizations usually adjust the rules to fit younger players. Typical adjustments are field sizes, game lengths, number of players per team, the number and frequency of substitutions, "offside" is sometimes not called, and slide tackling is sometimes not allowed. Field sizes, ball sizes, length of games and rules vary by age group. The FIFA rules do not require separate teams for girls and boys, but many soccer clubs and associations have separate leagues for boys and girls.
The "Laws of the Game" are not simple and can be difficult to understand. The official FIFA rules have 17 sections and the rule book is about 70 pages long. There are also an additional 44 pages titled "Questions and Answers". There is also the problem that the rules use many soccer terms and there are quirks, such as the fact that terms which are commonly used such as "Hand Ball", "obstruction", and "Linesmen" are not defined in the official rules. Another confusing aspect of the rules is the way "Fouls" are defined; basically, they are defined not only as "Fouls" but also in the rules regarding "Cards". For this reason, to understand "Fouls" you must also understand "Cards".