Tundra, a treeless region located in the Arctic or at high altitudes. Tundra occurring in the Arctic is known as arctic tundra, that at high altitudes is called alpine tundra. Both types are relatively flat, and they have similar climates and vegetation. The main difference between the two, besides location, is that permafrost (permanently frozen ground) underlies virtually all of the arctic tundra but is rare in alpine tundra.

Arctic tundra fringes the northern edges of Europe, Asia, and North America. It lies between the northern coniferous forest, or taiga, and the Arctic Ocean. Most of the arctic tundra is low-lying. Extensive bogs occur during the summer because permafrost prevents water from draining when surface thawing occurs.

Alpine tundra occurs throughout the world in high mountains, between the timberline and the snow line. In general, alpine tundra is well drained, but some marshes occur.

The tundra climate is severe, with extremely long, cold winters when temperatures almost never rise above 0° F. (–18° C.). Summers are short and frost may occur at any time; average temperatures of the warmest period rarely exceed 50° F. (10° C.). Precipitation, most of which falls as snow, is relatively light and usually amounts to less than 10 inches (250 mm) annually.

Because of the very short warm season in the tundra, plant life is limited to grasses, mosses, lichens, and shrubs. In the Arctic, plant growth is aided by the long daylight hours of the summer.

Because of the harsh climate, settlements in the tundra are few. Economic activities of people who live in the arctic tundra include hunting, fishing, nomadic herding, and mining. The main economic activity of people living in the alpine tundra is herding, especially of sheep.