Authentications are similar to Apostilles.

Authentications are certificates issued by the Department of Foreign Affairs and Trade (in Australia) verifying the signature and seal of the notary or the authenticity of an original document issued by a government official. Generally countries who are not signatories to the Hague Apostille Convention require an authentication. The documents are then provided to the Embassy or Consulate of the country of destination for a further legalisation process required by that particular country.

This results in a three step process rather than the two step process when countries are signatories to the Hague Apostille Convention.