Hi
@AnNguyen1612! Are you referring to the early decision? If you decide on an early decision program, then you are locked into that program. You cannot apply to other programs during the admission cycle. You can only choose one early decision program. Generally, early decision allows you to compete against less candidates because the admission committee of that specific school has less applications to go over. Furthermore, the committee knows that you made their school your first choice which increases the likelihood that you would be offered an interview. If however you do not get into that school as an early decision candidate, then you may apply for other schools.
I hope this helps!