According to the UNWTO's definition, ecotourism refers to forms of tourism which have the following characteristics: All nature-based forms of tourism in which the main motivation of the tourists is the observation and appreciation of nature as well as the traditional cultures prevailing in natural areas.

Basically, Ecotourism is a form of tourism involving responsible travel to natural areas, conserving the environment, and improving the well-being of the local people. (Source: Wikipedia)