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. They look like regular books except that they are glowing like other enchanted objects, and they have a red ribbon. The player can create an enchanted book by enchanting a book on an enchantment table, which will yield a single enchantment. Enchanted books can be found in chests located in dungeons, strongholds, mineshafts and villages. Enchanted books can also be obtained by trading with librarian villagers.

In Creative Mode, the books can be found in their appropriate tabs. (e.g Silk Touch in the Tools tab, Fire Aspect in the Weapons tab etc.)

Effective combinations
Here is the list of the irregular, effective combinations of enchantments and items.

History
In the 1.4.6 update, when you are in Creative, if you go into your inventory, go into tools, you will see 4 enchanted books, the 1st one being Efficiency V, 2nd one being Silk Touch I, 3rd being Unbreaking III and 4th being Fortune III. If you go into combat, you will see 18 enchanted books, just to name a few being Power V, Feather Falling IV, Fire Protection IV, Infinity I and Bane of Arthropods V.

Trivia

 * The player can enchant any block or item with any enchantments in Creative mode with the use of enchanted books and the anvil. As a result, for example, a dirt block with sharpness will do more damage, and a dirt block with silk touch can dig up grass blocks.
 * Combining a regular book with an enchantment on an anvil in creative will yield an enchanted regular book, not an enchanted book. However, combining two Enchanted Books will stack their effects into a new Enchanted Book.
 * Enchanted books do not exhibit their enchantment (e.g. attacking with Enchanted Book with Sharpness will not do more damage).
 * Enchanted books allow players to get normally unobtainable enchantments in Survival such as Silk Touch on shears or Unbreaking on a sword.
 * Enchanted books found in dungeons can contain any enchantment available to players including those normally only obtainable on books via the anvil - rank 5 of sharpness, bane of arthropods, smite, power and efficiency.