NIE stands for “Numero de Identificacion de Extranjero” (Foreigner Identification Number), it’s a unique number assigned by the Spanish authorities to non-Spanish citizens who reside in Spain, with the aim of identifying them and controlling their activities. It’s necessary to conduct any kind of process in Spain, such as opening a bank account, contracting public services, buying a vehicle or even buying a property. It’s important to note that the NIE is only valid as long as the residency in Spain is maintained, if the residency is lost, the NIE is also lost.