Apostille convention 1961
If the document is intended for use in a foreign country it has to be legalized for foreign use. This is a process in which various seals are placed on the document. The legalization procedure basically depends on one factor: whether the target country has joined the Convention Abolishing the Requirement of Legalization for Foreign Public Documents ("The Hague convention"). In this case the only legalization required is an Apostille certificate.
The Hague Convention of October 5, 1961, "abolishes the requirement of legalization for foreign public documents and facilitates public documents executed in one state to be circulated in another."
The international agreement envisages replacement of cumbersome and costly formalities of a full legalisation process with the issuance of an Apostille (also called Apostille Certificate). Apostilles can be issued by a competent authority designated by the state on whose territory the public document has been executed