Hello aspirant,

The Preparatory Courses is a one year ( 2 semester ) residential programmes and as the name suggests prepares the students to be eligible for the B.Tech or Dual Degree Courses at the IITs....

The Preparatory Course of the IITs is held primarily to improve the intake of SC/ST students in the B.Tech and Dual Degree programme....

You can check further information about preparatory courses from the following link....

https://engineering.careers360.com/news/iits-announce-preparatory-course-for-scst-candidates

Hope this helps

All the best for your Future !