Village

Villages, also known as NPC villages, are groups of buildings inhabited by villagers that spawn naturally in the world.

Generation
Villages generate naturally in plains, savanna and/or desert biomes.

Village behavior
A village is almost always composed of at least one acceptable house and one villager. In some rare cases, villages have spawned with a well and nothing else (This appears to occur very frequently on console versions). Upon creation, a village center is defined as the geometric barycenter of the active doors' locations, and the village's size is the greater of 32 blocks or the distance to the furthest door from the center. Any villager, village golem, or siege-spawned zombie will path back into the village if they find themselves farther than "size" blocks from the center.

As the villagers move around, the area near them is occasionally checked for new valid doors ("houses"). Thus, the random movement of villagers may also slowly change the center of the village they live in, even if no houses are actually changed. If a new valid door is found more than 66 blocks outside of any existing village's center, a new village is created; if a new valid door is found fewer blocks away than that, the door is added to an existing village and the center is recalculated.

The minimum population of a village is 0.35 times the number of valid doors (see below). If the population drops below that point (due to death or kidnappings), but there are at least two villagers left who can reach each other, the villagers will mate and breed until the population is above the minimum.

Adult villagers can be traded with by right-clicking/using interact button on them on PC/console. Currently trading is disabled in the Pocket Edition.

Advanced Village Placement
When attempting to place villages as close to each other as possible (for an iron golem farm for example) if their centers are to share the same x & y or y & z coordinate then the the remaining coordinate must differ by 66 or more. So for example village A at 0 64 0 and village B at 0 64 66 will not merge, but if village B is at 0 64 65 they will. For all other cases if the real distance sqrt(x2 + y2 + z2) between their centers is greater than or equal to 65 they will not merge. So if we want to build village C above the middle line between village A and B then their x difference is again 0 their z difference is now 33 so using our formula d2 = x2 + y2 + z2 or 652 = 02 + 332 + y2 then with a little algebra we find that their y difference must be at least 56 or in other words C's center should be at 0 120 33.

Symmetrical villages are easy to calculate the centers of, but for more complex villages such as naturally generated villages it's a good idea to give yourself a few blocks extra room. Try calculating from the position of the door closest to your build site.

Note: The integer rounding in the game's internal programming may allow villages to be placed one block closer under certain circumstances, but this formula will function to keep the villages apart every time. Also, if you're planning something really complex, try using the BBox Outline Mod to help visualizing.

Popularity
A player's popularity starts at zero, and ranges between -30 and 10, and the following can alter a player's popularity: A player's popularity does not reset on death, and players cannot alter other players' popularity. In addition, the popularity is stored per village; a player may have a high popularity in one village and a very low one in another. When a player's acts directly on a villager, particles around that villager will indicate the change in popularity.

Conversely, because popularity is stored per village, if the entire village is destroyed, any accumulated popularity, positive or negative, is also eliminated. This may be useful in synthetic village designs, such as when only one villager is kept in range of doors to maintain the existence of the village but is moved out of range in order to destroy the village, such as to stop infinite villager breeding.

Presently, popularity has one effect: if a player has -15 popularity or less, iron golems of that village will become aggressive to that player. If an iron golem is idle, it may become aggressive to the nearest player with -15 or lower popularity. However, "nearest" can be any distance at all, so if the village's chunks are loaded (perhaps by another player), the golems can turn hostile even after the unpopular player has traveled across the world.

Another feature further encourages players to protect villagers: if a villager dies to a non-mob, non-player source while a player is within 16 blocks, or if a monster kills a villager, then no villager in the village will mate for approximately 3 minutes.

Number and frequency of structures
The number of buildings composing a village can vary, and not every village is composed of all buildings at once. Apart from the well, which is unique and systematic, the number of buildings of each type is randomly generated, and increased in superflat worlds. Structures are picked from a weighted probability list (libraries are more common than butcher shops). There may be fewer buildings of a given type than the maximum allowed. The number of lamp posts has no restriction, as they are generated where no other buildings can be placed. Gravel roads are found between the buildings of the village and often extend beyond them.

Plains and Savanna
Village buildings in plains and savanna biomes will be made out of Oak Wood, Oak Wood Planks, Cobblestone, Cobblestone Stairs and Glass Panes.

The following blocks can be found in plains and savanna villages:

Desert
Village buildings in desert biomes are made out of Sandstone, Smooth Sandstone, Sandstone slabs, Sandstone Stairs and Glass Panes instead of wooden or cobblestone features. Also, the plains and savanna biome villages have Gravel roads while the desert biome villages have Sandstone roads.

The following blocks can be found in desert villages:

Loot
One or more slots in the chest that spawns in a Blacksmith Shop may be populated with items from the following list. There may be more than one slot containing the same type of item, but the numbers per slot do not exceed these limits:

Video
Note: This video is outdated, as desert villages now spawn with sandstone instead of wood and cobblestone.

History

 * Notch originally worked on Villages by himself, but eventually gave the task to Jeb, so that he could work on other things.
 * A picture of villages was released by Notch before Beta 1.8 was released. In the early screenshots, villages were partly made of Moss Stone.
 * Villages were shown to the public during the PAX 2011 demo, including the interiors.
 * Jeb has said that during early tests of villages, the lava in a smithy often set the village on fire.
 * An early interview with Notch discussed his plans for the village.

Trivia

 * Farms in the villages avoid overhanging by filling in the area below them with dirt. When the farm overhangs a ravine, this can cause a very tall rectangular dirt structure.
 * Occasionally, surface ravines will be generated through villages, causing missing pathways or even entire buildings sunken into the ravine. This also applies to cave entrances and other surface oddities.
 * The well acts as the "center" of the village in reference to Minecraft's code. If a well generates in a desert, all buildings and paths will be made of sandstone, even if all other buildings are in an adjacent plains biome. The well also appears to be the point where village-locating tools will point to. This explains why there is always exactly one well in each village.

Pocket Edition
Villages may generate very close to each other or even rarely double or triple.
 * Due to the absence of pressure plates in Pocket Edition, tables are made up of 1 fence and 1 brown carpet instead.
 * If a village spawns next to a river/lake, the gravel roads on water will be replaced by wooden bridges in Pocket Edition.
 * In Pocket Edition, the smithy tends to catch fire, which can spread to another house, because the fire did not receive an updated mechanic like how PC version was.