Much of the literature on ‘sustainability’ has different definitions. Given the different conditions of political, economic, socio-cultural, and environmental systems in which tourist destinations exist, the diversity is understandable. Thus, as mentioned by Bell and Morse (1999, p. 10), ‘having a single definition that one attempts to apply across this diversity could be both impractical and dangerous’. Nevertheless, a clear definition is needed in the initial stage of project implementation to avoid confusion or misunderstanding which is very common in this research area. Sustainability is a contingent term, that is, it is not just a static, descriptive term, like a colour. It implies that something is, or is not, happening. It could be said that sustainability is the ability to be sustained, that is, the ability to survive. With consideration of the current condition of system quality, Ten Brink, Hosper, and Colijn (1991), and Bell and Morse (1999) also emphasises the sequential process in assessing sustainability as discussed in Sections 3.1 and 4.7. Development is meant to improve human condition, and sustainable development should ensure the survival of a system at a higher level—otherwise, it is not worth doing. Tourism is a form of development, and therefore, the same criteria apply as for development generally. In these terms, this study would argue that: The sustainability of a system is the ability of the system to maintain a state of health necessary for survival. Sustainable development is development that enables the system in that it is located to maintain a state of health that is necessary for survival at a higher level of quality. STD is tourism development that enables the system in which it is located to maintain a state of health that is necessary for survival at a higher level of quality. In this case, the ‘‘ state of health’’ is defined as the condition of a system that is regarded as a desirable and acceptable standard for survival for a living system.