Because foreign countries do not have access to the record of your signature and role as a notary public, apostilles and certifications are used so that they can know if your official signature is authentic, what your role is, and what your seal means. By authenticating a document with an apostille or certification the Secretary of State is verifying that you have been granted granted “full faith and credit” to your seal and signature.
Hague Convention
In 1961 the Hague Convention eliminated the requirement of legalization for foreign public documents. Countries that have joined the Convention have access to simplified certification of public documents, including notarized documents.
Member countries have agreed to recognize documents from other countries as long as they are authenticated by an “apostille” and do not require any other diplomatic or consular legalization.
Certifications
If the document is intended for a country that is not a member of the Hague Convention then the Department of State will attach a certification. Unlike apostilles, certifications may require further diplomatic or consular legalization before they are sent outside of the United States. This may even include authentication by the U.S. Department of State and the Foreign Embassy of the country where the document will be used.
Apostilles and Certifications
Apostilles and certifications serve the same purpose, but the forms and the countries of use differ. If you perform the wrong one then your documents will be delayed. It is also required that you include the name of the country where the documents will be used.