Tariffs: a tax on imports or exports, quotas: a quantity restriction on imports or exports, export subsidies: a payment to producers that export, or...

Tariffs: a tax on imports or exports, quotas: a quantity restriction on imports or exports, export subsidies: a payment to producers that export, or through other regulations (e.g., product specifications) that discriminate against foreign products. Differences in labor productivity across sectors. Differences in relative supplies of factors such as capital, labor and land. What are the costs and benefits of these policies? Who gains and who loses?