This document provides an overview and introduction to the Global Sustainable Tourism Criteria (GSTC). It discusses how sustainable tourism concepts originated from changing views of the environment. It describes the stakeholders involved in developing the GSTC, including the GSTC Partnership coalition of 27 organizations. The goals of the GSTC are to establish a common set of globally applicable standards to define and measure sustainability in tourism, and to avoid "greenwashing". The four themes addressed in the GSTC are sustainable management practices, socio-economic impacts, cultural heritage impacts, and environmental impacts. Tourism businesses can use the GSTC to self-assess their sustainability performance.