In international macroeconomics, bilateral data refers to data capturing flows of economic activity between a specific origin and a specific destination. Origin and destination refer to a given geographical area, such as a city, a region, a country or even a set of countries, which share some common features. The scope of economic activities involving bilateral flows is quite large. It concerns, for instance, international trade, international migration, foreign direct investments, and portfolio investments, just to name the most prominent examples. This paper deals with the use of bilateral data in the context of international migration. The academic literature has recently made extensive use of this type of data to identify the potential determinants of the magnitude and the composition of the international flows of economic migrants between countries. To that aim, the literature has mainly relied on a very popular tool, the gravity model.