Skeleton

Skeletons are ranged, hostile mobs that shoot arrows at the player and any other mob that attacks it. Like zombies, skeletons spawn in dimly lit areas, and will burn when directly in sunlight (when the sun is 15 degrees or greater above the ground) unless they are swimming in water. The skeleton will not burn if not directly in view of the sun, e.g. underneath a tree. Since their initial introduction into the game, skeletons have received an AI update that has allowed them be about as "intelligent" as zombies, since they were both given similar AI updates. Skeletons can since now seek cover when on fire, and can perform many other "smarter" actions.

Appearance
A skeleton has gray bones, a skull head and has the same face as zombies, but with a different color and a mouth. In their right hand, they hold a bow. The skeleton's head was used on the Wither, only inversed.

Uses
Skeletons are an excellent source of bones (and bone meal) and can also drop arrows. Each skeleton will drop 0 - 2 bones and/or 0 - 2 arrows upon death. Although skeletons will fire arrows into walls and the ground, the player cannot pick up and re-use these arrows. Because of its valuable drops, skeleton dungeons are well sought-out for mob grinding purposes.

Creepers must be killed by a skeleton's arrow in order to drop a music disc.

Skeletons also have a 1/40 chance of dropping a bow only when they are killed by the player. There is a 1/5 chance the bow may be pre-enchanted with Power I. The bow will not be damaged if dropped by the skeleton.

Since snapshot 12w36a, skeletons will rarely drop their heads as a decoration block along with some other mobs, although rarely. A Wither skeleton will also drop it's head which can be used to spawn the Wither Boss. Wither skeletons spawn in the Nether, along with (albeit rarely) normal skeletons as of snapshot 12w36a.

Behavior
When skeletons are nearby, their presence is indicated by the soft rattling sound of their bones. Skeletons will chase any player they see within a 16 block radius. They will climb steps, navigate mazes, and traverse other complex obstacles in order to get close to the player. When they are within 8 blocks of the player, with a clear line of sight, they will stop chasing and start shooting the player with arrows. If the player moves more than 16 blocks away from the skeleton, it will cease pursuit. In the old versions, the skeleton would have started to "bunnyhop" around you while shooting arrows. This was removed in 1.2, because Notch and Jeb thought it was then harder to kill the skeleton. Skeletons will attempt to avoid damage from the player by continuously circling around them while in combat.

If a skeleton's arrow hits another hostile mob, that mob will then attack the skeleton the same way it would attack the player (with the exception of zombies and creepers, which usually manage to continue pursuing the player). So, if a skeleton shoots another skeleton, they will inevitably become locked in a duel until one of them dies or is attacked by a player. As of 12w34a this is the same for the Wither.

Skeletons do not have a melee attack, their only weapon is their bow.

Skeletons will attempt to avoid sunlight by running under shade or into water.

Combat
Cleanly killing a skeleton generally requires the use of a bow and arrows. Melee combat will usually result in the player getting hit by at least one arrow before dispatching the skeleton. However, when using melee methods, it is recommended to circle around the skeleton in a decaying orbit by using the a/d keys and the w key simultaneously. This is a good way to dodge the arrows while getting close enough to attack.

If ranged combat is not an option, it is possible to minimize damage by blocking with a sword. This strategy can be used effectively by blocking just before the skeleton shoots an arrow and rushing forward after the shot. Repeating this process even while the skeleton is in melee range will allow the player to kill the skeleton while taking as little damage as possible from arrows.

Going after skeletons while swimming is not advised, as the water will slow the player's movement down to the point of making them an easy target for the skeleton's arrows.

Skeletons, like zombies and zombie pigmen, can be damaged by splash potions of healing and also are damaged heavily by a sword with the smite enchantment.

Defensive measures
Skeletons are vulnerable to daylight (when not standing in water), lava, fire, falling, suffocation, and contact with cacti. They are also able to climb ladders. Surface skeleton populations can be controlled if the player regularly sleeps in a bed at dusk, since skeletons will spawn in the dark if given the chance to. Players can keep an ear out for the clicking and xylophone-like sounds of nearby skeletons in caves and use certain corners and tight spaces to their advantage.

Construction safeguards
Proper lighting around and inside structures is essential to preventing skeletons (and other hostile mobs) from spawning.

History
Skeletons were a hostile mob introduced to the game in Survival Test. They spawned randomly in new Survival maps and followed players when approached, much like zombies. They shot arrows with a purple/magenta colored shaft, appeared to fire arrows at a faster and more random rate, and shot 6 arrows outward a short range in all directions when dying. Arrows fired by skeletons at that time could be picked up and used by players. Skeletons took 5 hits to kill and could appear wearing NPC armor (that gave them no additional protection) and gave 120 points when killed.

In Alpha, skeletons would drop 0 - 2 arrows upon death. As of Alpha 1.2.0 (also known as the Halloween Update), skeletons hold a bow in their right hand.

As of Beta 1.2, skeletons can drop 0 - 2 bones in addition to arrows. These bones can be turned into bone meal, and mixed with other ingredients to make dyes or applied to wheat and saplings to mature the crop instantly. In Beta 1.4, skeleton bones could be used to tame wolves. As of Beta 1.6.6, bone meal applied to grass blocks will grow tall grass and flowers. As of Beta 1.8, a skeleton's bow is now larger and held more realistically (full-sized bows, two-handed, and pulling the arrow back) than in previous versions (in one hand) and they also fire arrows slightly slower. Their arrows however, will be shot with more force. This update also fixed a bug where skeletons would fire their arrows from above their heads.

Since Beta 1.9 pre 5, a splash potion of fire resistance can be used to spare skeletons from burning to death in the sun.

In the 1.2 weekly Pre-release 12w04a, the Skeleton AI was updated so they are smarter, i.e. if a skeleton catches fire in daylight, it will rush to the nearest shadow or body of water for safety. The same path finding AI that was added to the zombies in 1.2 weekly Pre-release 12w03a were added to the skeletons in 1.2 Pre-release 12w04a. Since 12w06a, there is a small chance that skeletons drop a Bow when killed. There is also a small chance that the bow will be enchanted.

As of 1.2, Creepers will ignore a skeleton's arrows and will continue to chase the player since the creeper also received an AI update. In snapshot 2w34a, the skeleton AI implemented into the wither.

As of snapshot 12w36a, skeletons can be found in Nether Fortresses along with Wither Skeletons.

Trivia

 * A skeleton that is wearing a helmet (regardless of other armor) will not burn in sunlight, similar to Zombies.
 * Skeletons' arrows will often miss the player if they stand perfectly still and the skeleton doesn't move.
 * Skeletons' legs have the same texture as their arms.
 * If alerted to a player's presence, skeletons can (and will) fire arrows backwards (behind them).
 * If the player is under a skeleton, it will shoot itself.
 * Skeletons may spawn on top of a spider creating a "Spider Jockey."
 * In Creative Mode, when a skeleton shoots an arrow at the player, the arrow bounces off and can hit the skeleton or other mobs. If it hits another hostile mob, it causes it to become hostile to the skeleton.
 * Skeletons can climb up ladders, but they will not shoot the players while climbing up. They do not use ladders to their advantage, and often simply use it if it is directly in front of them while in pursuit of the player.
 * A skeleton can kill itself with its own arrows if the player stays directly above it while flying in Creative Mode.
 * A skeleton hit by a splash potion of harming will gain health, however, when it is hit by a splash potion of healing it will lose health. It is also unaffected by potions of regeneration and poison. This is because skeletons are undead.
 * Skeletons cannot see the player through glass.
 * If a skeleton spawns via a Monster Spawner on peaceful, it can shoot an arrow at the player before it despawns. The arrow won't do any damage, though.
 * If a skeleton is attacked by another mob, then attacked by the player, the skeleton will be focused only on attacking the first mob that attacked it. (Unless the mob dies of course)
 * There is an unused Death sound in the game files, however, they use the Hurt sound on death.
 * Skeletons will not go in pursuit mode when it is under the shade at any time of day. When it reaches nighttime however, they will start giving chase.
 * If a skeleton shoots a Zombie Pigman, only the Zombie Pigman that was shot will attack the skeleton.
 * If you stand inside of the skeleton he can't hurt you, but you can hurt him.
 * In 1.8, skeletons held their bow with both hands, as seen in the picture below.