Sustainable travel is traveling in a way that contributes to the environmental, socio-cultural and economic values of the places one visits, and the planet at large.
Traditional, consumer-based tourism often does not take cultural or environmental aspects of travel into consideration. Tour operators sometimes can be exploitative of the locals and travelers can leave a large footprint in both the culture and environment of sites they visit. This is often unintentional, but the idea of sustainable tourism is for travelers to become more conscious and intentional of the ways in which they travel, so that the environment and cultures are better preserved.
Sustainable travel is not just about ethics or guilt, however. There is a vast difference between a tourist and a traveler; and such travel creates a much more enriching and meaningful experience for the traveler, as well. Rather than being shuttled from one tourist attraction to another, snapping photos of the local life passing by outside the windows of tour buses or five-star hotels, sustainable tourism provides the visitor the opportunity to truly be immersed in the culture and soul of the place.