Name Tag

A name tag is an item used to name existing mobs. It is used by naming the name tag using an anvil, and then right clicking any mob you want to name with the renamed name tag in your hand. Name tags have no crafting recipe and are only found in dungeons.

Usage and behavior
To use a name tag, it must first be renamed to the desired name with an anvil. The player can then right-click mobs to give the mob the name given to the name tag with the anvil. In survival, the name tag is consumed during the process. In creative, the name tag will not be consumed. The name tag will not be dropped by a renamed mob. To name horses using a name tag, however, a player must mount on a horse first and then right-click the horse with a name tag. Also, Villagers cannot be named using the name tags. You can only name villagers by renaming their spawn egg using the anvil. This was added in the Redstone Update. To rename a mob, just use another name tag on the mob. The new name will replace the old name. The Ender Dragon can not be named using the name tag.

Renamed mobs will have their name displayed over their head in the fashion as a mob named through a renamed spawn egg. Their names can only be seen if they are aimed at from 7 or fewer blocks away. Mobs that are named using the name tag will also not despawn in the world, similar to tamed mobs. Players can therefore use name tags to not only name mobs, but to retain them if players travel far distances.

Any mob (not including Villagers and the Ender Dragon) can be named. Even hostile mobs like the Wither or Ghast can be named. However, if you want to keep a named Zombie or Skeleton, be sure to keep it in a shaded area so it does not burn up in the sun. Endermen can be named as well, but they are not really worth the effort because they tend to just teleport away. Keep in mind that Hostile mobs will still attack you in survival, even if you named them.

Trivia

 * Name tags were added to the game primarily due to the request of popular Minecraft gamer Paul Soares Jr..
 * Name Tags with the exact same name will stack, while Name Tags with different names will not.