Relative to other forced migrants, refugees are in a privileged position in international law: they have legal status, rights under the 1951 Refugee Convention, and a specific organisation dedicated to their protection (UN High Commissioner for Refugees). Internally Displaced Persons, or IDPs, have a much less developed protection framework, even though the global population of IDPs is 59.1 million. So what explains this difference of treatment between these two categories of forced migrants?