Laws of the Game « Officiating « Soccer

FIFA.com: Laws of the Game - The rules of the sport as authorised by the International Football Association Board (IFAB). Also includes questions and answers and an interactive guide to Offside Law 11.
Ask The Ref Soccer Rules Explained - Answers to questions regarding soccer rules provided by an International panel of certified referees.
Burtrand World: Offside Rule - A simple explanation of the offside rule and the offside trap with the use of diagrams.
International Football Association Board - The body that determines the Laws of the Game. The board is made up from four FIFA representatives, and one representative each from England, Northern Ireland, Scotland and Wales.
Sheffield Rules - The rules were a code of football devised and played in the English city of Sheffield between 1857 and 1878.
Soccer Referee Info - A collection of links for known sources of laws, advice, training material and leagues. Geared at the developing referee who wants to learn more.