Apostille seals were introduced to the 1961 Hague Convention Abolishing the Requirement of Legalisation for Foreign Public Documents. The convention established rules governing the international recognition of legal documents. Not all countries are its treaty members.
An Apostille seal means the document can be used legally in a foreign country. However, only countries that signed Article 12 of the 1961 Hague convention will honour an Apostille. The rest or non-member states or countries may require legalization by the embassy or consulate-general.
Hague Convention members: Australia, Belgium, France, Germany, Greece, Hong Kong, Hungary, Italy, Japan, Macau, Mexico, Netherlands, Norway, Portugal, Republic of Korea, South Africa, Spain, Sweden, Switzerland, United Kingdom of Great Britain and Northern Ireland and United States of America. (See More Here)