Eye of Ender

An Eye of Ender is a craftable item the player uses to activate an End Portal via placing it on the End Portal Frame. It is also used to find the portal via leading the player to a Stronghold which the portal is within by right-clicking while holding it.

When thrown, it will float diagonally upwards for about fifteen blocks in the direction of the nearest Stronghold, emitting a trail of purple particles. It will float in the air for three seconds before either falling back to the ground as a collectable item or shattering into particles and disappearing. When the player throws it within twenty blocks of the Stronghold's portal, it will float toward the ground directly above the portal. If the Eye of Ender is hit by lightning, an Enderman will spawn.

Players traveling to the End are advised to craft multiple Eyes of Ender since each one has a chance of disappearing after being used to locate the Stronghold containing the portal and up to a dozen Eyes will be needed to activate it.

History
The Eye of Ender was first added as an item in Beta 1.9 Pre-release 3, but had no use until Beta 1.9 Pre-release 4, when each Eye could be placed in a portal block or used to home in on a Stronghold. Jeb demonstrated the new uses for an Eye in his livestream. An End Portal within a Stronghold could be seen in the stream with two Eyes inserted into blocks.

Trivia

 * Eyes of Ender were oddly large from third person or other players view in multiplayer. It also appeared to be held at a 90 degree angle from the original orientation. This is due to a programming error, which specifies that Eyes of Ender should be wielded as a "tool" in third person. This error was shared by Sugar.
 * The Eye of Ender's right-click function only works in the Overworld.
 * In 1.9 pre5, there is a bug when, if the eye is thrown, it will make both the arrow shooting sound and the egg throwing sound.
 * Another bug is, if you throw an eye while walking, it has a chance of crashing your game and corrupting the world in which you did so.
 * In older worlds, generated before 1.9 Pre-release 3, the eyes may mislead you to a place where there isn't a Stronghold at all.