An Apostille is needed for your documents to be recognized internationally and here more in detail why...
An Apostille is an International Notarial Document Certification issued by the U.S. Department of State, Secretary of State, Notary commissioning agency, Consulate Offices and Ministry of Foreign Affairs in the respective country validating the seal and signature of a notary on a document so that it can be accepted in a foreign country.
SIMPLY PUT it is an international seal that will be recognized by countries part of the Hague Convention such as the USA, Germany, Argentina, Canada, Serbia, Italy, Norway, Denmark to name a few. Even countries not part of The Hague Convention often will recognize an Apostille or require an authentication.
Why such complicated paper disaster…? It provides an additional layer of document authentication the Hague Convention Countries decided to recognize from each member country.
In Germany we would say doppelt gemoppelt hält besser “twice holds better”.