Here are Q&As about apostilles:
What is an apostille?
An "apostille" is a form of authentication issued to documents for use in countries that participate in the Hague Convention of 1961. A list of countries that accept apostilles is provided by the US State Department.
If the country of intended use does not participate in the Hague Convention , documents being sent to that country can be "authenticated" or "certified".
The Office of the Secretary of State provides apostille and authentication service to U.S. citizens and foreign nationals on documents that will be used overseas. Types of documents include corporate documents such as company bylaws and articles of incorporation, power of attorney, diplomas, transcripts, letters relating to degrees, marital status, references and job certifications, home studies, deeds of assignments, distributorship agreements, papers for adoption purposes, etc. The U.S. State Department provides general information about document authentications and apostilles under the Hague Convention of 1961.