The freedom to buy or sell in a market. Market access may not be available for natural or institutionally imposed reasons. Natural obstacles include distance and inability to meet the requirements of customers; institutional obstacles include legal restrictions on entry, tariffs and quotas, and public procurement rules excluding possible suppliers. Inability to compete on price may result from nature or policy; in increasing returns industries, lack of access to some markets limits total output and may cause high costs. Similarly, in industries where technical progress is partly due to learning by doing, past lack of market access contributes to present inability to compete.