Overworld

The Overworld is the starting area in Minecraft. It is the only dimension that has existed throughout the development of Minecraft. The Nether was the second dimension added, in version 1.2.0. The Sky Dimension is confirmed but not yet implemented.

The Overworld is the entire three dimensional space in which in-game construction can occur, encompassing the span from the level ceiling down to bedrock and extending in every direction on the horizontal plane. There are a number of tools that allow users to edit their map. Minecraft uses a Voxel system which is an incremental 3D grid in which each grid point holds data for a single block.

Sizes
The map can be randomly generated at the start of a game, unless it has been edited by the administrator of a server. The random generation of maps includes sheer cliffs, trees, caverns and hills.

Seeds on the other hand make a map that is generated using a complex formula. The map seems random, but is in fact generated using complex algorithms that refer to the seed entered at the beginning of the game. Part of the reason an infinite world can be generated and still take up very little space is due to this fact. If one was to share a world seed, which is just a sequence of characters that the computer converts to hexadecimal, anyone who used that world seed would generate an identical world to the previous seed, aside from any changes the players make.

In Classic and Indev, maps can be generated in "small" (128x128x64), "normal" (256x256x64), and "huge" (512x512x64) sizes.

In Infdev, Alpha and Beta maps are not infinitely big. They are made up of chunks; as the player explores the map distant chunks are generated automatically, leading to theoretically infinite maps. In practice, technical reasons force the maximum map size to 8 times the surface area of the Earth. Whilst the horizontal planes of the maps are vast in size, the vertical plane remains at a fixed 128-block height.

In recent versions, it is possible for the player to surpass the vertical boundaries of the map via pillaring upward or visiting the void in gaps of the bedrock downward. However, the player cannot place blocks above the vertical limit, and falling into the Void will eventually kill the player. Since the Halloween Update, it has become more difficult to find a path to the void.

Chunks
Chunks are the method used by Notch to divide "infinite" maps in the alpha and beta releases. They are 16 blocks wide, 16 blocks long, and 128 blocks deep, and is about 32,768 blocks total. When wandering the world the nearest 81 chunks are loaded, arranged in a 9 by 9 grid around the player. These chunks may have activity (mobs spawning, trees growing, water flowing, dropped items disappearing etc.), while the other world chunks are inactive, stored on your hard drive. If a player goes to an area that is beyond the already generated chunks, new chunks are generated and stored to the drive.

Biomes
Biomes are climatically and geographically defined as similar climatic conditions on the Earth, such as communities of plants, animals, and soil organisms, and are often referred to as ecosystems.

Natural Structures
The Overworld is able to seamlessly create new areas by using patterns found in the surrounding chunks and extend those into the newly created chunk. These patterns, while unique to each world, can be categorized easily by comparing them to a real-world equivalent, such as cliffs or oceans. While Minecraft is based on landforms found on earth, impossible formations, such as floating islands, can often be found throughout the Overworld.

Navigating the Overworld
Tools used for Navigating the overworld include the Compass and Map (Item). The player may also build landmarks to help orient themselves. Since version Alpha 1.2.3, the toggles a debug console which shows the player their absolute coordinates.

Minecraft includes a coordinate system which appears to correspond in a consistent way to the four cardinal directions (i.e. north, south, east, and west). This coordinate system may be used to aid in large-scale construction, to assist in tunneling between remote locations, to measure areas or structures, and to generally find your way in the world.

Clouds are defined as always traveling north and may be used to confirm north's true direction, if desired. East and west may be determined by the rising and setting of the sun, respectively. Based on the assumption that the sun rises in the east, testing indicates the following: The abundance of blocks of a specific type are related to Altitude.
 * The X value corresponds to the north-south axis, with one's coordinates decreasing as one travels north and increasing as one travels south.
 * The Z value corresponds to the west-east axis, with one's coordinates decreasing as one travels further east.
 * The Y value corresponds to the up-down axis, with coordinates increasing as one climbs higher in the world.

The South/West Rule may be related to the fact that traveling south or west causes one's horizontal spatial coordinates to increase; traveling north or east causes X- or Z-coordinates to decrease, respectively.

Light
Lighting in Minecraft affects visibility, Mob spawning, tree growth, and whether flowers and mushrooms will stay planted. Lighting can be provided by sunlight, torches, fire, lava, in-use furnaces, and other certain objects.

Also see: Day/night cycle

Nether
The Nether is accessible via Portal and can be used for quick travel on the above ground map. The Nether also contains Block types not seen anywhere else, as well as abundant supplies of Block types found on the normal world, like Mushrooms and Lava. The Nether is home to two Mobs very uncommon on the overworld: Ghasts and Zombie Pigmen.

Sky dimension
The Sky Dimension is a work in progress by Notch. It is now a confirmed update but the release date is not known. In a live webcast on the Swedish gaming site feber.se Notch revealed that the Sky Dimension would "probably be a dream world" and that when "you go to bed there is a certain chance that you get dragged into the dream world instead. Then you will be able to do it on purpose later on."

Void


The Void is the term given to the empty space beyond the generated boundaries of each map. It can be seen through gaps in the lowest layer of Bedrock on maps generated prior to the Halloween Update, but also simply by looking up from ground level, as the sky and the void are one and the same. For this reason, the void is a light source, and its brightness depends on the time.

Far Lands
The Far Lands is the area that forms the "edge" of the "infinite" map. When players make it to the Far Lands, they will experience an excessive amount of lag and the map will be severely distorted. According to Notch, this distortion can be fixed, but since no one is likely to make it to the Far Lands without some form of cheating, he says that he will likely not fix it since he likes the idea of a mysterious world beyond a certain distance.

Trivia

 * You can start a new world with the same map as a previous world by using the same seed.
 * There is a bug that sometimes causes the files for deleted worlds to not be deleted from your hard drive. If a new world is created with the same name, this can cause the game to reuse the old files, and thus, parts of the old map, rather than generate an entirely new map.