The Certers are a random event. Miles, Niles, or Giles present a player with a rotating image of an item, and three possible choices of what it is. If a player correctly identifies the item, they will receive coins, food, or gems. An incorrect choice will result in the player's weapons and note-able items being noted. Players may take advantage of this; they can drop any items they wish to keep, incorrectly answer, and have their ores, logs, or fish noted, allowing them to carry more.
In RuneScape Classic, the Certers were employed in Draynor, converting fish, ore, or logs into certificates. When the new RuneScape was introduced, the certers were removed from the game and replaced by the bank note system. Jagex released this random event as a reference to their old trade.