Here is the complete procedure for the counselling and admission process of IITs,NITs and IIITs :
Counselling and admissions process in IITs and IITs is offered by the JOSSA.JOSSA is a committee,provides a single platform for admission process in IITs,NITs,IIITs and many other colleges based upon the rank in JEE Advanced and JEE MAIN exams.
In NITs,IIITs,GFTIs and many other private college counselling will be based upon JEE MAIN rank while in the case of IITs it will be JEE ADVANCED rank.
:-Eligibility criteria to participate in JOSSA counselling process-
The candidates who have qualified JEE MAIN or JEE ADVNCED can apply for counselling process and also they should have at least 75 % from their respective board or under top 20 percentile.