Free trade is a trade policy that does not restrict imports or exports. In government, free trade is predominantly advocated by political parties that hold economically liberal positions, while economic nationalist and left-wing political parties generally support protectionism, the opposite of free trade.

Most nations are today members of the World Trade Organization multilateral trade agreements. Free trade was best exemplified by the unilateral stance of Great Britain who reduced regulations and duties on imports and exports from the mid-nineteenth century to the 1920s. An alternative approach, of creating free trade areas between groups of countries by agreement, such as that of the European Economic Area and the Mercosur open markets, creates a protectionist barrier between that free trade area and the rest of the world. Most governments still impose some protectionist policies that are intended to support local employment, such as applying tariffs to imports or subsidies to exports. Governments may also restrict free trade to limit exports of natural resources. Other barriers that may hinder trade include import quotas, taxes and non-tariff barriers, such as regulatory legislation.

Historically, openness to free trade substantially increased from 1815 to the outbreak of World War I. Trade openness increased again during the 1920s, but collapsed (in particular in Europe and North America) during the Great Depression. Trade openness increased substantially again from the 1950s onwards (albeit with a slowdown during the 1973 oil crisis). Economists and economic historians contend that current levels of trade openness are the highest they have ever been.

Economists are generally supportive of free trade. There is a broad consensus among economists that protectionism has a negative effect on economic growth and economic welfare while free trade and the reduction of trade barriers has a positive effect on economic growth and economic stability. However, in the short run, liberalization of trade can cause significant and unequally distributed losses and the economic dislocation of workers in import-competing sectors.