Annual Review of Economics Volume 10, August 2018.
Trade occurs between firms both across borders and within countries, and most trade transactions include at least one large firm with many trading partners. This article reviews the literature on firm-to-firm connections in trade. A growing body of evidence coming from domestic and international transaction data has established empirical regularities that have inspired the development of new theories emphasizing firm heterogeneity among both buyers and suppliers in production networks. Theoretical work has considered both static and dynamic matching environments in a framework of many-to-many matching. The literature on trade and production networks is at an early stage, and there are many unanswered empirical and theoretical questions.