You will have to take the Joint Entrance Examination – Advanced (JEE – Advanced) to get into IITs. Earlier it was known as the Indian Institutes of Technology Joint Entrance Examination (IIT-JEE).
It is the only admission test by the 23 Indian Institutes of Technology (IITs).
Prestigious Indian Institutes of Science Education and Research (IISERs), Rajiv Gandhi Institute of Petroleum Technology, and Indian Institute of Science also use the score obtained in JEE Advanced as the basis for admission so if you want to study in an equally good institute you should start your preparations right now.
The examination is organised each year by one of the various IITs.