Sustainable development is concerned with per capital utility or well-being, then population growth will mean that more and more output will be needed just to keep pace with additional numbers of people .Whereas technological change is likely to make capital more efficient, population is likely to depress some capital stocks and make sustainable development less feasible.
The condition for sustainable development, therefore, amounts to each generation leaving the neat generation a stock of productive capacity, in the form of capital assets and technology , that is capable of sustaining utility or well-being per capital than that enjoyed by the current generation.
The world commissions definition of sustainable development made it clear that the emphasis on future generation was only part of the story: Concern with the poor now was also important,indeed the highest priority. These questions pertain to the distribution of wealth within each generation. The analysis above can be applied to this equity issue as well, for the poor cannot improve their lot without access to productive capacity. If their well-being is to improve, then they must secure better education, better technology, more man-made capital, and more. Social capital will matter as well in the sense of the need for more participation in decisions that affect their lives, and more consultation. Control over resources can be facilitated by establishing secure property right to land and other resources.
Expressed simply, sustainable tourism can be defined as: "Tourism that takes full account of its current and future economic, social and environmental impacts, addressing the needs of visitors, the industry, the environment and host communities"
Conceptual definition Sustainable tourism development guidelines and management practices are applicable to all forms of tourism in all types of destinations, including mass tourism and the various niche tourism segments. Sustainability principles refer to the environmental, economic, and socio-cultural aspects of tourism development, and a suitable balance must be established between these three dimensions to guarantee its long-term sustainability.