Although VAT systems are generally built on the basis of a common set of core principles, such as the principles of neutrality and of destination-based taxation (see Chapter 1), there is considerable diversity in the actual design and operation of these VAT systems in OECD countries. This is notably illustrated by the wide variety of reduced rates, exemptions and other preferential treatments and special regimes that are widely used in OECD countries, for practical or historical reasons, to support certain economic sector or to achieve equity or social objectives.