Hi Aishwarya,

In the CET admission procedure, you are allocated a seat in the first round based on your preferences. Once you are given a seat, you have three options -

1) Freeze - Allows you to keep the seat you've been allocated, you are no longer a part of the allotment procedure.

2) Slide - Allows you to be upgraded to a course of your choice higher on the list of your preferences within the same institute3). 

 3) Float - Allows you to upgrade to a seat in a different college with a similar or different stream, canceling your previous allotted seat. 

Cheers.