When you appear for any entrance exam and cleared them then there is a process of choosing the best college to study according to your Rank in the entrance exam which is called as Counselling. Basically in a counseling a student fill preferred choices of college and a course. Like most proffered college first.Then there are more than one courses are offered by college.So in all one has to give a preference based on a particular course and a college.Then according to your score and seats availability, the respective course is alloted to you.

Hope this helps you :)