The National Institute of Open Schooling (NIOS), formerly National Open School is a national level board of education in India, controlled and managed by the Government of India.

[2] NIOS had a cumulative enrollment of about 15 lakh (1.5 million) students from 2004 to 2009 at secondary and senior secondary levels and enrolls about 3.5 lakh (350k) students annually which makes it the largest open schooling system in the world.

NIOS is a governing body just like any other Indian government official department [3] The NIOS collaborates with the Commonwealth of Learning (COL) and UNESCO.

[4] It also has study centres for Indian expatriates in the Bahrain, United Arab Emirates, Oman, Kuwait, Nepal, Canada, Kingdom of Saudi Arabia, Australia, United Kingdom, New Zealand, Malaysia, Singapore and the United States of America.

On Demand Exams are held through the year except for April-May and Oct-Nov i.e. when public exams are going on, ODE isn't held.