If you are going to Spain for study, work, or permanent residence, you may need to take with you the documents such as birth certificates, diplomas, criminal records and etc. To make your documents valid abroad, they are required to undergo the procedure of consular legalization or Apostille services. An apostille is the equivalent of an international notarial seal. Documents which bear an apostille are legally valid for use in all countries party to the Hague Convention on the Legalization of Documents. This includes both the United States and Spain.
Spain is a member of the Hague Apostille Convention and any official document destined for this country requires an Apostille.