It is mainly used for if statements, so you can check the player has a high enough faction before the quest continues:
	Code:
	sub EVENT_SAY
{
  if(($text =~ /Hail/i) && ($faction >= 3))
    {
      quest::say("Do you think I ave time to talk to people like you?.");
    }
  elsif(($text =~ /Hail/i) && ($faction < 3))
    {
      quest::say("Greetings, $name.");
    }
}