A biome is a relatively large division of the biosphere that has a distinct climate, particularly with regard to average annual precipitation and temperature, and that contains characteristic types of living organisms, especially vegetation. The climate depends on factors such as latitude, elevation and mountainous barriers. The major categories of biomes include: aquatic, desert, forest, grassland and tundra. Biomes typically lack distinct boundaries, but rather have transition zones called ecotones, which can share species from both biomes as well as species specific to the ecotone.
Ecosystems differ from biomes in that they are the interaction of living and nonliving things in a specific area through food webs and energy flows, whereas biomes are geographic regions distinguished by the broad categories of species living in them. A biome can be composed of many ecosystems: for example, an aquatic biome can contain ecosystems as diverse as kelp forests, coral reefs and intertidal zones.