Skeleton

A skeleton is a fairly fast-paced enemy that will shoot arrows at the player and any mobs that attack it. Like zombies, skeletons spawn in dimly lit areas, and will burn in daylight (when the sun is 15 degrees or greater above the ground) unless they are swimming in water or are standing in the shade. For example, underneath a tree, outcropping of a mountain or player-built structure. As of Minecraft version 1.2, the skeleton has received an AI update that lets them be about as "smart" as zombies, since they were both given similar AI updates. Skeletons now seek cover when on fire, and can perform many other "smarter" actions.

Appearance
A skeleton has white bones, a skull head and they have the same faces as zombies, but with a different color. In their right hand they hold a bow.

Uses
Skeletons are the sole source of bones (and bone meal) and can also drop fully formed 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. There is also a small possibility of them dropping the bow they are holding. The bow may be enchanted.

Creepers must be killed by a skeleton's arrow in order to drop a Music Disc.

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

Behavior
Skeletons will chase any player who comes within a 16 block radius, even if they can't actually see the player (in other words, they can see through walls). 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.

If a skeleton's arrow hits another hostile mob, that mob will then attack the skeleton the same way it would attack the player. So, if a skeleton shoots a Creeper, it will chase the skeleton and explode when it gets close enough. If a skeleton shoots another skeleton, they will inevitably become locked in a duel until one of them dies.

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.

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.

Skeletons that have shot neutral or hostile mobs will be attacked by that mob, use this to your advantage and have a zombie follow you to a skeleton, the skeleton will shoot the zombie and the zombie will attack the skeleton. Chances are the zombie will win, with the skeleton's loot there for the taking.

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. Also as of Beta 1.8, bone meal can also be used on a mushroom to create Huge Mushrooms.

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. Here's a video showcasing the path finding changes.

Since 12w06a, there is a small chance that skeletons drop a Bow when killed.

Trivia

 * Skeletons cannot hit the player if they stand perfectly still and the skeleton doesn't move.
 * Skeletons' legs have the same texture as their arms.
 * If the player is under a skeleton, it will shoot itself.
 * A skeleton in a Minecart will burn on contact with sunlight.
 * 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.
 * If a skeleton shoots itself with its own arrow, the arrow does not stick to the skeleton.
 * 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.