Foreign direct investment (FDI) occurs when a firm invests directly in facilities to produce or market a product in a foreign country. There are three main types of FDI: acquiring or merging with a foreign firm, creating a new 'greenfield' operation abroad, or establishing a foreign subsidiary. FDI gives firms significant control over their foreign operations and allows them to affect managerial decisions. FDI has increased over the last 20 years as globalization has expanded firms' visions of foreign markets and circumvented some trade barriers. However, FDI declined sharply in 2001-2002 due to economic slowdowns and geopolitical uncertainty.