National Insurance number
The National Insurance number is a number used in the United Kingdom in the administration of the National Insurance or social security system. It is also used for some purposes in the UK tax system. The number is described by the United Kingdom government as a "personal account number".
Social security in Spain
The social security system (Spanish: "seguridad social") in Spain is its principal system of social protection. The concept of social security first appeared in Spain in 1883 under the Committee for Social Reform, it was expanded several times during the twentieth century and finally the right to social security was enshrined in the Spanish Constitution of 1978 under Article 41 which states "that the public authorities shall maintain a public social security system for all citizens, guaranteeing sufficient support and social benefits in situations of need, especially in the event of unemployment, and that the support and additional benefits shall be free".