The Stolper-Samuelson Theorem explains how changes in trade can affect income distribution among different factors of production. Specifically, it shows that if a country opens up to trade, the real income of the factor used intensively in the export sector will increase, while the real income of the factor used intensively in the import-competing sector will decrease. This theorem is closely linked to the Heckscher-Ohlin model, which highlights the role of factor endowments in determining comparative advantage and trade patterns.