Ecotourism has been defined as a form of nature-based tourism in the marketplace, but it has also been formulated and studied as a sustainable development tool by NGOs, development experts and academics since 1990. The term ecotourism, therefore, refers on one hand to a concept under a set of principles, and on the other hand to a specific market segment. The International Ecotourism Society (TIES) (previously known as The Ecotourism Society (TES)) in 1991 produced one of the earliest definitions:
“Ecotourism is responsible travel to natural areas that conserves the environment and sustains the well being of local people.”
IUCN (now called the World Conservation Union) states in 1996 that ecotourism:
“is environmentally responsible travel and visitation to relatively undisturbed natural areas, in order to enjoy and appreciate nature (and any accompanying cultural features - both past and present) that promotes conservation, has low negative visitor impact, and provides for beneficially active socio-economic involvement of local populations.”