If you participated in the Destiny beta, you may already be familiar with the rules. For freshly-resurrected Guardians however, here's the jist: in normal Crucible (see: PvP) matches, there are limits placed on a player's gear to prevent victory and defeat from being determined by the loot you or your foes have amassed. In the Iron Banner playlist of PvP matches, no such limitation exists. This means the dedicated loot farmers and equipment hoarders of the galaxy are likely to have an advantage over those less-equipped.
Your rewards, should you excel in this particular event, will be high-level weapons and armor, emblems and special color schemes for your Guardian's armor. If you don't already have equipment with awe-inspiring numbers attached to it, might we suggest you take a tour of Destiny's fabulous, loot-filled caves?