Every individual born in metropolitan France or its overseas departments is assigned a unique number by the National Institute of Statistics and Economic Studies (INSEE). This number, known as the NIR, is then entered into the National Directory of Identification of Natural Persons (RNIPP). Informally, it is often called the “social security number.” INSEE explains that this unique number consists of 13 digits, representing respectively the gender (1 digit), the year of birth (2 digits), the month of birth (2 digits), and the postal code of birth (5 digits). The following 3 digits indicate a sequential number used to distinguish individuals born in the same place at the same time, and finally, a 2-digit check digit completes the NIR.