Well, an apostille is a certificate attached to the official by the government in question. These certificates are used to certify the notarized documents for a foreign country that participated in the convention. The convention was held in Hague, Netherlands. It was decided that if a country is a part of a convention, the citizen can apostille their official documents; it will legally verify the documents in other countries that are members of the convention, as well. The purpose of getting the apostille of the documents is to reduce the requirements and long procedure of international paperwork.
