"Early Decision (ED) is a binding method of admission by which students apply early to a single school — usually their first choice — and pledge to attend if accepted. In an email to the Daily, Karen Richardson, dean of undergraduate admissions and enrollment management, stated that she expects at least half of the Class of 2022 will come from the ED applicant pool.
History of early admission programs
According to documents obtained from the Digital Collections and Archives, in the 1959-1960 bulletin, a new heading of ‘Early Decisions’ was introduced." …
https://tuftsdaily.com/features/2018/03/01/early-bird-applicant-trends-early-admissions/