It usually is called a penalty and is showed by a yellow flag.
A warning, indicated by a verbal admonishment, or a caution, signalled by showing a player or substitute a yellow card.
A red card, or ejection
They are technically called assistant referees.
3 referees are in soccer and football
The Official, besides being able to Caution a player with a Yellow Card or Expel a player from the field (Red Card), may also choose to warn the player of what he feels is not reckless or dangerous enough to warrant either a yellow or red card. Usually this means listening to the Referees reasoning of why he/she is warning you.
Referees
yes
Soccer referees are graded by levels, not by classes. Informally, a referee might be considered "Class A" if they are certified International referees.
Green card in soccer means that when a player respects the referees' decision and be a sportsmanship person
In soccer, a foul is when a player commits an unfair or illegal act against an opponent. Referees determine fouls by observing the game and enforcing the rules set by the governing body of soccer, FIFA. Fouls can result in free kicks, penalties, or even player ejections depending on the severity of the offense.
There is a dot net website called Soccer Referee Information or SOCREF. This site is intended to be a source for information for current and aspiring soccer referees.
The answer is obviously. Yes.