An Apostille is a validation stamp used by countries that have signed the Hague Convention on Civil Documents that enables a legal document issued in one such country to be recognized as legal in another. Both the U.S. and Slovakia have signed this particular convention.
According to the Hague Convention, a document originating in one Convention country is recognized in all other Convention countries if it bears something called an “Apostille”. (Details on the Convention itself and a list of countries that have signed it) An Apostille is a certification by a superior office in the country where the document was issued attesting that the official who issued it had the authority to do so.
Joe was born in Florida and needs to submit a legal copy of his birth certificate to the Slovak government in order to apply for a residency permit. He has already obtained a Certified Copy of his birth certificate from the appropriate office in Florida. Now he needs to obtain an authentication from the “Secretary of State of the State of Florida”.