Zombie

A zombie is a hostile mob with green skin and clothes that closely resembles the player. A zombie measures 2 blocks tall, 1 block wide, and 0.25 blocks thick. Zombies spawn in dimly lit areas and attack players by shambling towards them and touching them. A zombie, along with skeletons will catch on fire when in sunlight

Uses
As of Minecraft Beta 1.8, zombies drop 0-2 pieces of Rotten Flesh. Before the update, they gave 0-2 Feathers instead.

Behavior
Zombies moan when wandering around aimlessly, but snarl and gurgle when attacking and injured. Zombies spawn in groups of 2 - 6 and will pursue the player on sight, making no attempt to avoid cliffs or other obstacles, which they will try to breach by hopping. Unlike skeletons, zombies do not try to avoid being hit, and will continue to pursue the player.

At dawn (when the Sun is 15 degrees or more above the ground), zombies will catch on fire and burn. However, if they are in a body of water when this time comes, they will not be burned, as the water will douse the flames. If they exit the water and the conditions for them burning still are true, then they will catch on fire, although if they are in enough shade (under a tree, cave, etc.), they will not catch fire.

Combat
Zombies are one of the easiest enemies to deal with and don't pose much of a threat unless encountered in a narrow space or in large groups. A player on sufficiently high ground can repeatedly hit a zombie again and again as it approaches. If the player is being pursued by several zombies, they can use a sword to push them back with each hit, alternating targets so no single zombie can close in. If a player is in a small room with several zombies with no escape route, it is recommended to use blocking and slashing at the zombies to half damage and slowly kill the zombies.

As of Beta 1.9 Pre-release 5 Zombies, Zombie Pigmen, and Skeletons can be damaged by Splash Potions of healing and/or regeneration.

Defensive Measures
Like skeletons, zombies are vulnerable to daylight, lava, fire, and contact with cacti. Surface zombie populations can be controlled if the player regularly sleeps in a bed at dusk, since zombies will spawn at night if given the chance to do so.

Should a player be trapped on the surface outside at dusk, they can dig a single block wide pit 3 blocks deep, seal off the top with a block, place a torch at their feet, and wait for morning light to burn away the undead before climbing out.

History
Zombies were the first and fastest mob in Survival Test in the game until spiders were added, and could run as fast as the player. They would occasionally appear wearing armor, but this had no protective effect on their health. When killed, zombies gave 80 points each to the player.

The zombies' armor was removed in Indev. From Indev through Beta 1.7.3, zombies dropped 0 - 2 feathers upon death. Before chickens existed in Minecraft, Notch confessed that he made zombies drop feathers because he had no idea what they should have dropped when killed.

Trivia

 * Because a zombie has identical dimensions to the player model, the zombie's skin can easily be used as a player skin and vice versa.
 * A Giant is an unused variation of a zombie that can only be spawned through third party programs. Its behavior is identical to the zombie's, but it has 50 hearts of health, deals 8.5 damage in one single hit, and is unable to damage you unless you are right under it.
 * In 1.0, a splash potion of fire resistance can be used to spare zombies from burning to death in the sun.
 * In 1.0, a zombie 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. This likely happens because zombies are undead.
 * Zombies are easily detected through walls and blocks, due to their constant growling and moaning.