Enchanted Book

An Enchanted Book is an item which allows players to add enchantments to weapons, tools, or armor by combining the enchantment book with one of said items on an anvil. The player can create an enchanted book by enchanting a book on an enchantment table. It is a book with the enchantment "glow" and a red ribbon.

Unintended Functionality (12w49a)
Enchanted Books can currently be used with items they shouldn't be usable with, e.g., you can enchant placeable blocks. This section outlines the consequences of using Enchanted Books on items they were not meant to be used on; intended usage of Enchanted Books does not result in any of these issues.

Enchanted books only work on non-enchanted items.

Enchanted books do work on item stacks, after which the items will no longer stack with the same item having a different/none enchantment.

Some enchantments do not work, like flame or power ( on either normal items and snowballs)

Efficiency and Silk Touch do work, but only on items that you can get drops from. So a dirtblock with EFF V does not work on stone but does on wood.

Underwater breathing does work on every worn item, but only the highest counts. Probably same for feather falling.

Fortune does not work on shears.

Things that do work are Sharpness, Fire aspect, Looting and probably more.

Enchantments are lost after changing the item. Emptying an enchanted bucket removes the enchantment. Enchantments are also lost after placing the block.

Bugs

 * There is currently a glitch that allows enchanted books to enchant ANY obtainable item in the game.