Drop Rate  

ZAM Network Wikibase™ Dictionary

Drop is a general term and refers to items that you find on or near monster corpses (the mechanic varies from game to game). Drop Rate is a number or word that indicates how frequently a specific mob will drop a specific item from his loot table.

• Common Drop - Always or nearly always drops. Not always, but say 9 out of 10.
• Uncommon Drop - Frequently drops, 1 in 2 to 1 in 10
• Rare Drop - You could kill a lot of these mobs before you find one! Anything worse than 1 in 20 definitely qualifies. Droprates in this class should be a legal defense for dev-icide.