To actively cancel or stop something directly.
When to use
Subject cancels directly, Active action, Canceling appointments
The nuance
Used when the subject actively cancels a plan, appointment, or event.
취소하다 (chwi-so-ha-da, chwisohada) · 취소되다 (chwi-so-doe-da, chwisodoeda)
취소하다 (chwisohada) is active, meaning the subject cancels something directly, while 취소되다 (chwisodoeda) is passive, indicating something gets canceled.

One lane per word — no nested boxes, just the gist.
To actively cancel or stop something directly.
When to use
Subject cancels directly, Active action, Canceling appointments
The nuance
Used when the subject actively cancels a plan, appointment, or event.
To be canceled passively, without the subject's direct action.
When to use
Passive cancellation, Independent of subject's will, Cancellation by system or external factors
The nuance
Used in passive situations where cancellation happens to the subject.
회의를 취소했다.
hoe-ui-reul chwi-so-haess-da., hoe ui reul chwi so haess da.
The subject actively canceled the meeting, so 취소하다 is correct.
회의가 취소되었다.
hoe-ui-ga chwi-so-doe-eoss-da., hoe ui ga chwi so doe eoss da.
The meeting was canceled passively, so 취소되다 is correct.
나는 약속이 취소했다.
na-neun yak-sok-i chwi-so-haess-da., na neun yak sok i chwi so haess da.
The appointment is the object, not the subject, so active 취소하다 can't be used. Correct: '약속을 취소했다'.
약속이 취소되었다.
yak-sok-i chwi-so-doe-eoss-da., yak sok i chwi so doe eoss da.
The appointment was canceled passively, so 취소되다 is correct.
나는 예약이 취소되었다.
na-neun ye-yak-i chwi-so-doe-eoss-da., na neun ye yak i chwi so doe eoss da.
'예약이 취소되었다' is passive; if subject is 'I', correct form is '예약을 취소했다'.
예약을 취소했다.
ye-yak-eul chwi-so-haess-da., ye yak eul chwi so haess da.
The subject actively canceled the reservation, so 취소하다 is correct.
행사가 취소되었다.
haeng-sa-ga chwi-so-doe-eoss-da., haeng sa ga chwi so doe eoss da.
The event was canceled passively, so 취소되다 is correct.
행사를 취소되었다.
haeng-sa-reul chwi-so-doe-eoss-da., haeng sa reul chwi so doe eoss da.
Active 취소하다 cannot be used with a subject in a passive sentence.
Which sentence requires '취소하다'?
Which sentence correctly uses '취소되다'?
Which sentence has a different meaning from '예약을 취소했다'?