Zombies and Skeletons are the simplest monsters in Minecraft, so they will be sharing an article. They also share a quality, which is another reason for this.
Being undead, both Zombies and Skeletons will catch fire in sunlight. This is only true for sunlight, not torchlight, so don’t try planting torches to get them to burn to death. They will take damage while they are on fire, just as anything else. However, if a Zombie or Skeleton is in water at the same time as they are in the sun, the water will put out the fire constantly, preventing them from taking any damage at all. Additionally, recent updates have made it possible for zombies and skeletons to avoid catching fire by being in the shade, either from a tree, rain, or simply being under enough cloud cover. Because of this, anyone fighting the undead on the surface needs to be careful if they’re relying on sunlight to give them a hand.
Zombies have as many hit points as you do, and very light armor. They are dangerous only in melee combat- although they have the added threat since the 1.2 update of being able to break down doors (iron doors are safe if your difficulty is less than Hard, because of their durability). Fortunately, they are not terribly intelligent or agile- they will head as directly towards you as they can, moaning and meandering. They will avoid dropping into lava and sometimes dodge around pits, and can jump just like you- but they are a bit slower than you are, and aren’t terribly bright about going around obstacles. Their attack range is slightly less than yours, so if you are facing only one zombie you are fairly safe standing still and swinging at it as it enters range.
Zombies will drop rotten flesh, and occasionally may drop basic iron equipment or iron ingots- but mostly it’s just rotten flesh.
Skeletons are considerably more dangerous than Zombies. Although they lack the armor that the Zombie bears, the Skeleton has a very useful piece of equipment- the Bow. Skeletons attack by shooting arrows at you. Despite this, they do still advance towards you, with the same degree of intelligence as the Zombie. However, there is more to their threat than the ability to shoot at you from a distance (and at any angle).
Skeletons will, when advancing on you, juke to the side when they shoot so as to avoid counterattacks. They will also run, making them considerably faster than zombies. As if that weren’t enough, they also jump while they are attacking, making them still harder to hit. Just to add insult to injury, skeleton arrows travel in a straight line rather than a falling arc, making it that much harder to avoid being shot by them.
Running around a skeleton or ducking behind a corner to lie in wait are pretty much the only two ways to get a skeleton into melee combat without putting yourself through a lot of harm from their arrows. Moving slowly near a skeleton is never advisable; if you have to fight a skeleton, make sure you don’t do it while you’re in water, or you’ll get shot up even worse- and may not ever make it -to- the skeleton. Skeletons will seek cover just as you ought to, so don’t expect to have a clear shot at one even if you have got a bow of your own.
For all the extra danger, Skeletons are much more frail than Zombies, so if you can get one into melee range the fight is probably over. Skeletons are also very valuable kills- they are the only source of Bones in the game, and will often drop arrows when they die. If you kill a skeleton, there is also a slim chance it will drop a bow- and the bow will be in perfect condition. The usefulness of bones and bone meal, and the value of bows, means that while they are more dangerous than Zombies most players will actively pursue chances to kill Skeletons- and you should too.
Just be careful about it.