Horse

Horses are a planned 1.6 mob hinted by Jeb when Minecraft hit 10,000,000 sales. DrZhark, creator of the Mo' Creatures mod assisted with the horse's creation, which is the same from Mo' Creatures.

Once a horse is tamed and a horse saddle is attached, they can be controlled with standard directional controls and the mouse. Different variations of horse armor can be put onto horses. They can be tied to fence posts using a leash. There are different breeds of horses, similar to the different breeds of cats. A foal's growth can be accelerated via the use of apples, wheat, sugar, hay bales. Horses are completely passive when hit, unlike other mobs.

Appearance
There are currently 5 variations of the horse mob in the game. The normal horse are all the same breed and can be 1 of 7 base colors; gray, dapple gray, dark bay, bay, flaxen chestnut, buckskin, and black. The horses also have a secondary coloring known as markings. There are 4 different markings; stockings, snowflake appaloosa, pinto, and black blanket. In total there are 35 possible horse color combinations taking into consideration all base colors and markings (also noting a horse can be just a base color with no markings). There is also the donkey which can be bred with a horse to produce the mule. There are two other types of undead horses: a zombie horse and a skeleton horse, but they cannot be tamed by the player, and can only be brought into the game by editing the region files.

Horses and foals
Horses are the regular horse breed in the game, and occasional foals will spawn too. They can wear horse saddles and can wear any horse armor. Foals can be fed apples, wheat and sugar to grow faster, however sugar makes them grow a little slower than an apple.

Mules and donkeys
Donkeys are a different variation of horses, and are less common than horses when spawned. Young donkeys and mules can be fed apples and sugar in the same manner as horses. They can wear a horse saddle, but not horse armor. Instead, they can wear a chest, but the inventory is not accessible (yet). Upon death a donkey or mule will drop the attached chest. Mules can be made by breeding a horse with a donkey, which seems to work more rarely than normal horse and donkey breeding. Mules themselves do not appear to be able to breed. (Probably because in real life, mules cannot breed because horses have 64 chromosomes, donkeys have 62. Therefore when breeding the offspring has 63 chromosomes, and is sterile.)

Skeleton
It is a skeleton variation of a horse. It does not appear to be tameable. Has only one texture and cannot equip anything.

Undead
A zombie variation of a horse. It does not appear to be tameable. On the texture they have more of a leather pack than a chest.

Taming
To tame a wild horse, approach it and right click on it with an empty hand. You will climb on top of it, and will likely be thrown off. The taming appears to be sped up by feeding the horse any of the approved foods (apples, wheat, sugar) either while on the horse (before it throws you off), or when you are standing next to it. After a few attempts, it will allow you remain on it. At this point you can dismount it by pressing the Sneak key and place a Horse Saddle on it.

Riding
Once you have tamed a horse and put a horse saddle on it, you can control it with standard directional controls and the mouse. Horses can be made to jump, and holding the jump key allows you to charge your jump. Horses are not affected by Jump Boost beacons. Sneaking causes you to dismount, as does going in water deeper than two blocks.

When you mount a horse, the hunger bar and oxygen bar are replaced by the horse's health in survival or adventure mode. It uses a slightly different heart texture than the player's health bar. The experience bar is replaced by the horse jump bar, which gauges how high you jump. The maximum jumping height, which is reached when the bar is fully charged as you release the spacebar, depends on the horse you ride. It seems to range from about 1.5 to 5.1 blocks tall.

You can use any item while riding a horse, including drinking or throwing potions, activating doors or redstone devices, or using chests, crafting tables, and furnaces. You can also break and place blocks and attack. This also allows you to heal your horse with a carrot while you ride it.

When running forward, you will start at a slow walk and build to a speed faster than sprinting. You will automatically run up any one block high slope. You are three blocks tall while on a horse, but you can ride under 2 block tall areas, causing your head to pass through blocks. This causes suffocation damage, except when passing through non-solid blocks. You are slightly wider than one block, and are unable to walk through one block wide gaps. However, due to the horse's length, you can run over any one block gap. It also appears you can run across a two block gap at high speeds, but this does not seem to work all the time. You can also cause your horse to climb ladders by running at it similar to how players climb them.

Breeding
Horses are bred by feeding them wheat while you're riding them, but they cannot breed if they're wearing armor.

Once you have bred two horses you have a chance that the offspring is going to have better properties like having more health.

Trivia

 * The Horse is the only mob created with the help of a mod maker.
 * An interesting trick you can do while riding a horse is to get on your horse, press F1 on your keyboard, drink a potion of invisibility, and press F5. It will look like you are the horse, instead of riding on the horse.
 * This can be used to trick other players that you are a horse, so they probably wouldn't recognize you, which makes horses a great mob disguise.
 * This also works with pigs, but you can only control it with a carrot on a stick, making other players see you holding a item when you are invisible.
 * A player can jump a distance of at least 8 blocks while riding a horse as long as the jump bar charged up at least to the beginning of the orange part of it. (A distance of 9 blocks still needs more testing, but it has not been possible up to now)