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. Thus, sustainable tourism should:

   

Make optimal use of environmental resources that constitute a key element in tourism development, maintaining essential ecological processes and helping to conserve natural heritage and biodiversity.
Respect the socio-cultural authenticity of host communities, conserve their built and living cultural heritage and traditional values, and contribute to inter-cultural understanding and tolerance.
Ensure viable, long-term economic operations, providing socio-economic benefits to all stakeholders that are fairly distributed, including stable employment and income-earning opportunities and social services to host communities, and contributing to poverty alleviation.
- UNEP
Sustainable Tourism refers to a level of tourism activity that can be maintained over the long term because it results in a net benefit for the social, economic, natural and cultural environments of the area in which it takes place.

- ICOMOS
The United Nations World Tourism Organisation defines sustainable tourism as tourism that meets the needs of present tourists and host regions while protecting and enhancing opportunity for the future. Rather than being a type of product, it is an ethos that underpins all tourism activities. As such, it is integral to all aspects of tourism development and management rather than being an add-on component

The objective of sustainable tourism is to retain the economic and social advantages of tourism development while reducing or mitigating any undesirable impacts on the natural, historic, cultural or social environment. This is achieved by balancing the needs of tourists with those of the destination

- WTO
Sustainable tourism is tourism that is economically, socioculturally and environmentally sustainable. With sustainable tourism, sociocultural and environmental impacts are neither permanent nor irreversible.

- John Beech and Simon Chadwick

Sustainable tourism - Tourism that has minimal impact on the environment and culture of the host community.

- John Beech and Simon Chadwick