What is IIT preparatory course?

The Portions of IITJEE are generally based on CBSE Class 11 and Class 12 Syllabus but you must join some good coaching Institute like FIITJEE, Bansal Classes, Brilliant Tutorials, Aakash IITJEE etc.. to boost your chances of getting into IIT.Then after completing your class 12 you have to write the IITJEE Exam and clear it. Then you will be able to get admission in IIT.