What is an Apostille? 

An Apostille is specialized certificate of authentication recognized by countries who belong to the Hague Convention Abolishing the Requirement for Legalization of Foreign Public Documents. It provides a uniform method of validating documents to be used in foreign countries. It only authenticates the origin of the underlying public document. Apostilles authenticate the seals and signatures of officials on public documents such as birth certificates, notarials, court orders, or any other document issued by a public authority, so that they can be recognized in foreign countries that are parties to the Convention.

What's the difference between an apostille and certification?

Both are forms of authentication and both are given by the same government agencies. The difference lies in whether the country where you will use your documents belongs to the Hague Convention or not. If it does, your documents will receive an apostille, and if not, they will need a certification and may need further notarization from a foreign consulate or embassy. Here is a list of the countries currently listed with the Hague Convention:

A document with an Apostille does not require additional certification by the U.S. Department of State or legalization by a U.S. embassy or consulate overseas to be recognized in a participating country. 

All Apostille’s must be numbered consecutively, with individual numbers applied to each Apostille issued and contains 10 mandatory references: name of country from which the document emanates, name of person signing the document, the capacity in which the person signing the document has acted, in the case of unsigned documents, the name of the authority that has affixed the seal or stamp, place of certification date of certification, the authority issuing the certificate, number of certificate, seal/stamp of authority issuing certificate and signature of authority issuing certificate.

An Apostille or Certificate of Authentication issued by the New York Secretary of State is a one-page document with a blue laser printed facsimile of the New York Department of State Seal. Both the Apostille and Certificate of Authentication include the facsimile signature of the New York Secretary of State.

All Apostille's issued by New York State Secretary of State can be verified here.