What are the 4th Official duties?
 

I saw a pregame conference and there were four soccer officials. I have only seen three before - referee and two "line judges" (not sure of teminology).

So what does the fourth official do?

Also, I see where the line judges can talk to referee during game. Do they "suggest" calls that should be made that referee couldn't see. The referee has a very difficult job and can't possibly see all that is going on.

FIFA.com - The Laws of the Game - page 53

A fourth official may be appointed under the competition rules and officiates if any of the three match officials is unable to continue, unless a reserve assistant referee is appointed. He assists the referee at all times
• Prior to the start of the competition, the organiser states clearly whether, if the referee is unable to continue, the fourth official takes over as the referee or whether the senior assistant referee takes over as referee with the fourth official becoming an assistant referee
• The fourth official assists with any administrative duties before, during and after the match, as required by the referee
• He is responsible for assisting with substitution procedures during the match
• He has the authority to check the equipment of substitutes before they enter the field of play. If their equipment does not comply with the Laws of the Game, he informs the referee
• He supervises the replacement balls, where required. If the match ball has to be replaced during a match, he provides another ball, on the instruction of the referee, thus keeping the delay to a minimum
• He assists the referee to control the match in accordance with the Laws of the Game. The referee, however, retains the authority to decide on all points connected with play.
• After the match, the fourth official must submit a report to the appropriate authorities on any misconduct or other incident that occurred out of the view of the referee and the assistant referees. The fourth official must advise the referee and his assistants of any report being made
• He has the authority to inform the referee of irresponsible behaviour by any occupant of the technical area
• A reserve assistant referee may also be appointed under competition rules. His only duty shall be to replace an assistant referee who is unable to continue or to replace the fourth official, as required

The guys with the flags are assistant referees, but the old term of linesman is still used by lots of fans. Their primary responsibility is to rule on offside violations and when the ball is out of play.

ARs do look for things the referee can't see. They are assigned an area of the field in which to look for fouls that the referee does not see and will use their flag to ask the referee for a foul (and at this level the referee is going to grant the request nearly every time). All four officials also wear headsets to talk to each other if needed, and the ARs' flags have buttons on them that "buzz" a pager worn by the referee.

Thanks for the answers.