Drops

Drops are items which appear when mobs die. There are three basic types of drops: normal drops, rare drops, and Experience Orbs. Only normal drops appear when a mob is killed other than by the player.

Normal drops
Normal drops may occur whenever a mob dies, and appear at the location of the mob at the moment it receives the killing damage. Each mob has particular items which it may drop when killed.

For each of these items, there is a random (uniform) distribution of numbers of that item it will drop; for example, a Cow will drop 0-2 Leather items and 1-3 Raw Beef items. Since the range includes 0, it is possible for no leather to be dropped. If the mob is killed with a weapon with the Looting enchantment, then the upper limit of the range is increased by the level number of the enchantment.

If a mob is a baby animal, it will not drop anything when killed.

Rare drops
Rare drops occur in addition to the normal drops. Unlike normal drops, they only occur if the monster is killed by a player, similar to Experience Orbs. All rare drops can also be obtained by other means; there are no items which are exclusively available through rare drops.

Rare drops have a 2.5% chance of occurring when a monster dies, and a 20% chance of being enchanted rare drops. Using a weapon with the Looting enchantment increases the chance of a rare drop by 0.5% per level, and also increases the chance of enchanted weapons (up to 50% with Looting III). All types of non-enchanted rare drops are equally likely.

When items are enchanted, the enchantment is chosen in the same way as using an Enchantment Table with a cost of 5 levels. It is possible to get multiple enchantments.

Experience Orbs
Experience Orbs drop only if the mob is killed by a player. They always drop in a group of 3 with varying value, but their total value will always be the specific amount of experience granted by killing that mob.

Experience Orbs are similar to items but not the same. Unlike other drops, Experience Orbs appear at the location of the mob's corpse at the moment it disappears in a puff of smoke. Experience Orbs will move towards nearby players.

History
Experience Orbs were added in Minecraft Beta 1.8 (the Adventure Update).

Rare drops were added in Minecraft 1.2.