Apostille is a French word meaning certification.

The Indian document use in the HCCH member countries of the Hague convention, It must be legalised by the Ministry of External Affairs India. It is a special stamp called an Apostille. Apostille is simply the name for a specialised certificate, issued by the the Ministry of External Affairs. The Apostille is attached to your original document to verify it is legitimate and authentic.

MEA is the exclusive authority to issue Apostille Stamp to the India issued Certificate. Apostille documents are valid only in The Hague Convention Countries.
The Hague Convention 1961 abolished the requirement of repeated Legalization of foreign public documents by the governments of HCCH member countries.

Documents Apostille required for seeking Overseas immigration or Higher Education or Commercial/Business purpose or employment/family visa. In this information, you will get everything about apostille. The complete guidance of process, cost and how much time does it take to get apostille done in India

The HCCH 85 Members countries and another some countries are accepting Apostille Document. 

The Hague Convention was signed on 5th of October, 1961 in the town of Luxembourg. However, it only became effective from 14th of January, 1965. The Hague Convention Abolishing the Requirement of Legalization for Foreign Public Documents. So no required diplomatic (Embassy/Consulate) legalization of certificates for the legal communication among HCCH member countries of the Hague convention.  The Certificates only need to be stamped with an “apostille” by the Ministry of External Affairs. 

For Apostille Services in India, As the Ministry of External Affairs is not accepting documents directly from the individual/applicant, Certificates for the purpose of Apostille or Attestation by MEA are to be submitted and collected from the four designated outsourced agencies. W.e.f. January 01 2019, Apostille Attestation services have been decentralised to Branch Secretariats/RPOs in 15 cities New Delhi, Mumbai, Ahemdabad, Bengaluru, Hyderabad, Bhopal, Chennai, Kolkata, Chandigarh, Panaji, Cochin, Guwahati, Lucknow, Raipur and Thiruvanantapuram.