Rolling admission is a policy used by many colleges to admit freshmen to undergraduate programs.
Many law schools in the United States also have rolling admissions policies.
[1] Under rolling admission, candidates are invited to submit their applications to the university anytime within a large window.
Students can finish their application anytime between the summer before their senior year and midway through their senior year and can submit it at leisure, taking the time to carefully review their application and not getting anxious about a nearing deadline.
Other times, universities may underestimate the number of students who will take the offer of admission, resulting in the number of spots filling rapidly; this can lead to more-qualified applicants being denied, in turn putting pressure on students who wait a little longer.