In some parts of the tropics, ordinary houses for living are built in trees or elevated on stilts to the same level as the trees, to keep the living quarters above hazards at ground level. They can also be used for storing food out of reach of scavenging animals.
Tree houses are the only solution for building of eco-friendly facilities in some remote forest-areas. The wildlife, climate and illumination on ground-level in areas of dense close-canopy forest is not suitable for human habitation.
As of 2007, there are over 20 architectural businesses in Europe and North America that specialize in building treehouses of various degrees of permanence and sophistication, from children's play structures to fully-functioning homes.
Tree houses are also built out of recycled materials and lived in by environmental protest communities all over the world. They are used as a method of defence, as it is difficult and costly for companies to evict the protesters and commence destruction of the environment.
Although they have traditionally been of wood, experimentation with new technologies and innovative fabrics has led to the development of viable temporary living structures that are more like "tree tents" than tree houses. These have recently been used by scientists documenting the flora and fauna of the little-researched upper canopies of tropical forests.
