What is Sustainable Tourism?

What is Sustainable Tourism?
Some definitions:

”Sustainable tourism development meets the needs of the present tourists and host regions while protecting and enhancing the opportunity for the future.It is envisaged as leading to management of all resources in such a way that economic, social and aesthetic needs can be fulfilled, while maintaining cultural integrity, essential ecological processes, biological diversity and life support systems.” _ World Tourism Organization

“Tourism, which is developed and maintained in an area in such a manner, and at such a scale, that it remains viable over an indefinite period and does not degrade or alter the environment (human and physical) in which it exists to such a degree that it prohibits the successful development and well-being of other activities and processes.” _ Mr Richard Butler, 1993