A wilderness is an area of land that has been largely undisturbed by modern human development. Wilderness areas usually lack roads, buildings, and other artificial structures. They provide a natural environment for plant and animal species, and allow scientists to study healthy ecosystems.

Very few places on Earth are complete, or pristine, wildernesses. A wilderness can be reclaimed or restored, and the way a wilderness is managed can change at any time.

There are wilderness areas in every ecosystem, on every continent. The Great Barrier Reef in Australia, the worlds largest coral reef, is an aquatic wilderness that is home to dozens of endangered birds, fish, mammals, and reptiles. The Mavuradonha Wilderness in Zimbabwe features elephants, zebras, and crocodiles in their natural habitat.

Some wilderness areas are huge. Most of the continent of Antarctica is one big wilderness. Some wilderness areas are small and often located in unexpected places. Ernest E. Debs Regional Park is a wilderness area in the large, densely populated urban center of Los Angeles, California, United States.

The WILD Foundation, an organization dedicated to preserving wilderness areas around the world, defines a wilderness in two ways. Wilderness is biologically intact, meaning the natural biodiversity of a place exists in some form. Wilderness is also legally protected, meaning a government has laws to limit people from developing the wilderness.

People have lived with nature for thousands of years. Because of human population growth and development, many wilderness areas are threatened. The effects of human interaction with wilderness areas can be direct, such as a campfire or poaching. The effects can also be indirect, such as human contribution to climate change. A change in climate can limit native plant growth or lead to the growth of non-native species. Water or air pollution from a nearby development also may threaten wilderness areas. Nearby development may prevent animals from migrating. This not only reduces the number of animals in an area, but can often prevent the pollination of certain plants, further reducing biodiversity.

In order to protect wilderness, some governments limit human interaction with the area. They also limit the kinds of human activities inside a wilderness area, placing restrictions on mining, logging, or even traveling by car.

There are two different ways to manage a wilderness area. The first is conservation, which encourages sustainable use of natural resources. Many wilderness areas have limited access to logging, for instance. This could mean a timber company can cut down a small number of trees each year if they replace the trees with saplings (young trees). It could also mean opening up the wilderness area to individuals for chopping down Christmas trees.

The other type of wilderness management is preservation, which encourages people to preserve the wilderness by not using natural resources.

The government of the United States has legally protected more than 800 wilderness areas totaling nearly 452,799 square kilometers (174,826 square miles). The smallest wilderness area is Pelican Island Wilderness in the state of Florida. It is approximately 0.022 square-kilometers (0.009 square miles). The largest wilderness, by comparison, is Wrangell-Saint Elias Wilderness in the state of Alaska which is about 38,170 square kilometers (14,738 square miles).