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.