Apostille certificates are a result of the Hague Convention, a treaty between over 100 countries that allows documents issued in one country to be accepted in another. The authentication of public officials' signatures on documents are made in order to be used outside the United States of America.
Notarization is the act of officially certifying a legal document by a public notary. The purpose of having a legal document notarized is to ensure the authenticity of the signatures that appear on the document. Notarized Documents are valid for use inside the US.
Notarization is always included in the Apostille, as it is a main requirement for obtaining the Apostille. A a notary must witness the translator's signature on the translation and the document being translated is submitted along with the notarized translation for authentication.
Apostilles are used whenever public documents need to be produced abroad. This may occur in a multitude of cross-border situations: international marriages, international relocation, applications for studies, residency or citizenship in a foreign State, inter-country adoption procedures, international business transactions and foreign investment procedures, enforcement of intellectual property rights abroad, foreign legal proceedings, etc.
The situations where an Apostille is needed are countless. As a result, several million Apostilles are issued around the world every year, making the Apostille Convention the most widely applied of all the Hague Conventions. You can check which countries are part of The Hague Convention here.