Biomes are regions in a Minecraft world with varying geographical features, flora, heights, temperatures, humidity ratings, sky colours and foliage colours. Introduced in the Halloween Update, biomes separate every generated world into different environments, paralleling the real world; examples of biomes include the forest, jungle, desert and tundra. Prior to the Halloween Update, every world had only a single theme, either grassy or snowy.
The term biome is analogous to its scientific usage: on Earth, a biome is climatically and geographically defined by distinctive communities of plants, animals and soil organisms supported by similar climatic conditions. They are often referred to as ecosystems.
 Biome types
There are 12 main biome types and a number of technical biomes. Main biomes can be distinguished by the grass and leaf colors in the biome, along with the types of blocks present (e.g. types of trees or other plants like cacti, sand coverage in deserts). Biomes are pseudo-randomly generated using the map seed. Technical biomes provide smoother transitions between main biome types, or introduce extra custom features within a main biome, such as rivers, beaches, hills and border areas.
|Name and Features||Description and Sample Image|
|Forest||A biome with a lot of trees, occasional hills and a fair amount of grass. Oak and birch trees grow in this biome. Mushrooms, tall grass, roses and flowers can occasionally be found. Forests can occasionally be generated as a technical biome in plains biomes. This is one of the best biomes to start out in, due to the abundance of wood. The frequency of trees makes it dangerous to navigate at night, due to obscured vision, and ease of mobs to spawn. Forest biomes are also one of the smallest biomes.|
|Desert||A barren biome consisting mostly of sand, large dunes, dead bushes and cacti. Sandstone is commonly found underneath the sand. Rain never falls in this biome. Sugar Cane can be found if the desert is next to an ocean or river biome. The lack of visual obstruction makes mobs highly visible at night. Desert NPC Villages, desert wells and desert temples are found exclusively in this biome. Lakes do not generate in this biome, since snapshot 13w17a.|
|Plains||A relatively flat biome with rolling hills and much tall grass but with few trees. Gullies, water holes, and NPC Villages are common. Passive mobs spawn here often. Cave openings and water or lava springs are easily identifiable due to its unobstructed terrain.|
|Swampland||A biome characterized by a mix of flat, dry areas (including lots of small islands) around the sea level and shallow pools of water with floating lily pads. Clay, sand and dirt are commonly found at the bottom of these pools. Trees are often covered with vines and can be found growing out from the water. Mushrooms spawn abundantly in this biome. Stalks of sugar cane can be found along the shores. The colors of the water, grass, leaves and vines are much darker than in other biomes. As of 1.4, witch huts spawn in swamps. Slimes will also spawn naturally during the night.|
|Jungle||A very dense, tropical biome. It features large jungle trees that can reach up to 31 blocks tall with 2×2 trunks. Oak trees are also common. The landscape is lush green and quite hilly, with many small lakes of water often nestled into deep valleys, sometimes above sea level. Leaves cover much of the forest floor—these "bush trees" have single-blocks of jungle wood for trunks, surrounded by oak leaves for foliage. When inside a jungle, the sky will become noticeably lighter. This is the only biome containing ferns and the aforementioned jungle trees. Vines are found alongside most blocks and may be found close to the surface in caves. Ocelots, Jungle Temples and Cocoa Plants spawn exclusively in this biome, the latter found on jungle trees. Warning: If you have a slow computer or OS is 90% full or more, venturing into a jungle may crash Minecraft, or worse, your computer.|
|Ice Plains (Tundra)||An expansive, flat biome with a huge amount of snow. It does not rain in this biome — it snows instead. Lakes and rivers are frozen over. Hills tend to be more mountainous. Sugar Cane will spawn in this biome, but tend to become uprooted when chunks load as the water sources freeze to ice. There are very few natural oak trees in this biome. Due to the scarcity of wood, initial survival becomes difficult in comparison to other biomes. No above ground structures spawn here.|
|Taiga||A hilly biome densely filled with spruce trees. Grass is a dull gray-blue. Snowfall occurs in this biome, forming snow and ice. Hills are common, and wolves are found in this biome.|
|Extreme Hills||A highly mountainous biome (with some mountains reaching over y=100) with dull gray-blue grass and a few scattered oak trees. Cliffs, peaks, valleys, waterfalls, overhangs, floating islands, and many other structures exist, offering outstanding views. More underground cave systems are present here than in any other biome. Falling is a significant risk, as there are many ledges and sudden drops large enough to cause severe fall damage or even death. Extreme Hills and Extreme Hills Edge are the only biomes where Emerald Ores spawn. They are also the only true biome in which silverfish can be found naturally.|
|Ocean||An extremely large, open biome made entirely of water, with underwater relief on the sea floor, such as small mountains and plains, usually including dirt, sand, and clay. There is no maximum limit to the size of oceans. Oceans typically extend under 25,000 blocks in any direction, reaching out to 100,000 in rare circumstances. Small islands with infrequent vegetation can be found in oceans. Friendly mobs do not spawn on these islands, but hostiles do. Epic caves are very common below sea level, and entrances to underground ravines can be found at the bottom of the ocean, as well as abandoned mine shafts. Oceans can also be generated as technical biomes, appearing as deep ponds on beaches.|
|Mushroom Island|| This rare biome consists of a mixture of flat landscape and steep hills and has mycelium instead of grass as its common surface block. However, if you do place down a Grass Block, it is a very bright green color compared to other biomes. It is always adjacent to an Ocean and it is often found isolated from other biomes. It is the only biome where huge mushrooms can spawn naturally, and where mushrooms can grow in full sunlight.
No mobs other than Mooshrooms spawn "naturally" in this biome, including the usual night-time monster spawns. This also applies to caves, abandoned mine shafts, etc. below mushroom biomes, meaning exploring underground is relatively safe. This includes player-made structures as well.
This biome is commonly found in the middle of ocean biomes, however, it can be found rarely attached to the mainland.
Trees can be grown from saplings in this biome, as well as other dirt or grass-based plants, as long as they are not directly adjacent to mycelium, which will take over the dirt square from the plant and uproot it. Mycelium cannot be tilled directly, but it can be dug away and replaced as dirt, then immediately tilled. Once created, farmland can resist takeover by mycelium.
|Hell (The Nether)||This is the biome used to generate the Nether. Most of the terrain is composed entirely of expansive netherrack mountains, caves, and walls at all altitudes, though also spawns Nether Quartz. Unlike other biomes it is enclosed by bedrock at layers 128 and 1. Lava oceans cover this biome at layer 31, while lava springs flow down from the bedrock ceiling (and occasionally from walls), making lava streams and lakes very common. Besides generating more often, lava also flows further and faster than it does in the Overworld. It is the only biome where ghasts, blazes, wither skeletons and magma cubes naturally spawn. Glowstone is also found beneath netherrack ceilings and outcrops, while gravel and soul sand appear in layers and outcrops. Many of the creatures and resources of the Nether can only appear in Nether fortresses (the dark structure in the picture).|
|Sky (The End)||This biome is used to generate the End. Unlike other biomes it is composed almost entirely of a finite, floating landmass of End Stone, with the exception of obsidian towers and Ender Crystals. Only Endermen and a sole Ender Dragon can spawn in this biome. Using this biome in the Overworld (using external editors or superflat codes) will cause the sky to turn black.|
 Technical biomes
Technical biomes are found alongside or within their larger counterparts. They are not considered true biomes but they are referred to as biomes in the code and the debug menu. However, these technical biomes serve an important role in the Minecraft world in creating more realistic terrain.
There are seven known technical biomes,although there are less-technical biomes.
|Name||Description and Sample Image|
|River||A biome that consists of water blocks that form in an elongated, curving shape similar to a real river. Rivers cut through terrain or separate the main biomes. They attempt to join up with ocean on the other side, but will sometimes loop around to the same area of ocean. They have no current. Rivers are also a reliable source of clay. These biomes are good for fishing.|
|Frozen River||This variant of the river only spawns in tundra biomes. The surface layer of water is frozen.|
|Beach||Generated on the shores of oceans, beaches are composed of sand. Beaches penetrate the landscape, removing the original blocks and placing in sand blocks. These are also useful for fishing. Beaches are usually a lot bigger in a Taiga biome.For the history of beaches, see the Beach page.|
|Mushroom Island Shore||Mushroom shores represent the flat shore area of the mushroom biome.|
|Frozen Ocean||Found near snowy biomes, frozen oceans contain ice on the top layer of water.|
|Extreme Hills Edge||Acts as a fringe between mountains and most other biomes.|
|Hills||Hills are generated within Forest, Taiga, Desert, Jungle, and Tundra biomes and are referred in the F3 menu as "ForestHills", "TaigaHills", etc. Forest hills seem to be generated more rarely than the other hills in their respective main biome. Tundra Hills are usually taller, with height comparable to Extreme Hills biomes. In update 1.3 hills generated in forest and desert biomes are now taller.|
 Biome numbers
- Main article: Data values#Biome IDs
Each type of biome, including technical biomes, has its own biome number, shown in the following table. These biome numbers are used when creating a customized superflat world.
|20||Extreme Hills Edge|
 Biome history
- Main article: History of biomes and generated structures
Notch, when he was the lead developer of Minecraft, wanted to add biomes, but he couldn't for a long time. He says the intersection points looked terrible and so, biomes weren't added in the Seecret Updates.
|1.8||Biomes got an overhaul, removing some biomes, such as the tundra and the taiga, and others replaced with nine fractal-based biomes that were a mix of the previous biomes and new biomes.|
|1.0||Re-added tundra and added Mushroom Islands.|
|1.1||Re-added snow in taigas, added hills and beaches.|
|1.2||Added Jungle biome.|
|1.3||Hills in forests and deserts are taller.|
|1.6||13w17a||Water lakes no longer spawn in deserts.|
 Anvil file format
The Anvil file format allows for biomes to be stored in the world data. In contrast, the Region file format relies on the seed to dynamically calculate biome placement. This would cause biome placement in older worlds to change when the biome generation code was changed. With the current Anvil format, the biome data is stored along with the rest of the world data, meaning it will not change after the world is generated and can be edited by third-party map-editing tools. Furthermore, "edge" biomes allow for biomes to continue extend beyond the edge chunks of an old world. This allows for smooth transitions in world generation after the generation code changes in an update.
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Wikipedia, The Free Encyclopedia, "Biome", accessed 20 April 2012
Dictionary.com Unabridged, "biome", accessed 20 April 2012