There has been a proliferation of private sector initiatives to set standards and certification programmes for foods since the early 1990s, especially in industrialized countries. A major driving force behind these initiatives has been changing consumer preferences. Rising purchasing power, education level, urbanization and evolving lifestyles combined with the decline of food prices relative to other goods have led to changes in consumption patterns. While in the past price and visual aspect were the main purchase criteria, the intrinsic quality of food has become a much more important parameter. In addition to the physical quality of foods, consumers are increasingly demanding on the ethical dimension of food quality. This relates to the process of production and trade and its broad impacts on society and the environment. It includes a wide range of social, environmental or cultural issues such as the treatment of workers, a fair return to producers, environmental impacts and animal welfare. These concerns have developed partly as a reaction to the industrialization of agriculture, the concentration of food production and trade in large companies and the resulting globalization of food trade. They have been fuelled by non-governmental organizations (NGOs) campaigning for social and environmental goals such as the preservation of rainforests, labour rights or fair-trade. Some of these NGOs have developed voluntary standards that firms may choose to adopt to meet these concerns.