Aid is an international operation channelling tens of billions of dollars to developing countries each year and employing large numbers of people in a multitude of organisations.1 This chapter first describes how aid has grown through various stages, from modest origins in the nineteenth century to being securely established following the Second World War, fuelled by the inertia of institutions created in the aftermath of the war (including the success of the Marshall Plan), the cold war and the wave of independence from 1945 onwards. Since then further changes have taken place in institutions (the rise of multilaterals in the 1970s and NGOS in the 1980s), types of aid (the decline of food aid and the rise and fall of financial programme aid) and aspects of donor ideology (mainly the perceived role of the state). These changes are discussed throughout the various chapters of this volume. Together with Chapters 1 and 2, this chapter provides the backdrop for the analysis by presenting an overview of the history of aid as well as the particular features of aid and their changes over time, considering volume, composition, allocation, tying and financial terms.