One of the most difficult rules to learn in all team sport, offside is misunderstood by many beginning players and casual fans.  The following video offers a simplified explaination of Law 11.   

What is a hand ball and what isn't?  Another debated rule.  The following video explains the key considerations referees have to make in assessing a hand ball.  Also, regardless of a fan or player's interpretation, the referee has the complete discretion in determining whether any foul was committed at all and the severity of any fouls called in regards to and context of the Spirit of the Game (Law 4: the referee)