Free trade is an economic system or policy stance advocating for the unrestricted exchange of goods and services across international borders, characterized by the absence or minimal application of artificial barriers like tariffs, quotas, and subsidies. As a central concept and research domain in economics and international relations, it investigates the theoretical underpinnings and empirical consequences of such unrestricted trade, analyzing its effects on national and global economic welfare, resource allocation efficiency, industry structure, and international economic relations.