When do I apply advantage or award a penalty try?

• Advantage is the period after an infringement in which the non-offending side has the opportunity to gain territorial or tactical advantage, or a try.
• Where a defender is offside at a tap or rollball and attempts to interfere with play, the referee allows advantage or awards a penalty, whichever is of greater advantage to the attacking team.
• If the attacking team, while taking the advantage, then infringes, the ruling on the initial infringement applies.
• For a forward pass, the penalty goes to the defending team at the mark where the ball was propelled forward, unless advantage is applied.
• Penalty try: awarded if any action by a player, team official or spectator, deemed by the referee to be contrary to the rules or spirit of the game, clearly prevents the attacking team from scoring a try. A penalty try is also awarded if a player enters the field during a restricted interchange (after an intercept or line break) and prevents a try, and that player goes to the sin bin.

Source: FIT Playing Rules 5th Edition, definitions and rules 11.1, 17.7, 18.9 and 19.