What is Foreign Trade Barriers

Products and firms are homogeneous in traditional foreign trade theories; products show no horizontal or vertical differentiation. It is observed that growth in exports is only related to an increase in export quantity and that this is not decomposed into margins. Since Melitz's work, there has been an increase in studies that decompose the firms' heterogeneity and export growth in foreign trade into extensive and intensive margins. The concepts are addressed in the literature known as “new-new” foreign trade theories which include extensive margins, the number of exporting firms, the number of new trade partners, and the volume or variety of exported products. In brief, the growth of global trade is the result of new trade relations (extensive margin) or a rise in existing trade relations (intensive margin). As one of the rapidly developing trade theories in international economics, the main purpose of this study is to conduct a literature survey on the extensive and intensive margins of export growth.