What is Foul?
Foul meaning A foul is any infraction of the Laws of the Game which is called by the referee. The Laws of the Game are published by FIFA and its members (USSF for example). Throughout the Laws, you will see phrases such as “at the discretion of the referee” or “in the opinion of the referee”. Because the game is free-flowing and there are no time-outs in soccer, decisions must be made based on what the referee and their assistants see at the time. So where a spectator may see a foul, the referee may not always see the same thing, at the same time!
reference: NC Youth Soccer: Soccer Glossary. Words and terms of the game