Tagging refers to a mechanic for drop and experience distribution. Monsters come in two varieties: taggable and untaggable. Taggable monsters will award experience and drops to the first player to attack them. Untaggable monsters will divide the experience based on damage dealt by each player and generally give the drops to the player who dealt the most damage.
Monsters that can be tagged will display an asterisk (*) next to their name when attacked.