This document defines and discusses foreign direct investment (FDI). It notes that FDI includes mergers and acquisitions as well as building new facilities. There are three main types of FDI: horizontal FDI which duplicates activities in new markets; platform FDI which uses one country as an export base; and vertical FDI which moves across different value chains. The document also examines factors that influence FDI decisions like market access and efficiency, and discusses advantages like technological development and disadvantages like lack of skills development in host countries.