Apostille certificates and authentication certificates both validate the Notary's seal and signature on a document for acceptance in a foreign country. Apostilles, governed by the Hague Apostille Convention of 1961, involve a single certification issued by the Secretary of State. Authentication certificates are used for non-Hague Convention countries, requiring multiple certifications from various authorities, including your commissioning agency, the U.S. Department of State, the consul of the destination country, and potentially another official in that country.