This is the 19616th most frequent Korean word.
어제부터
"Since yesterday."
Here, '어제부터' (since yesterday) marks the starting time of a continuous action—raining—indicating it began yesterday and is still continuing.
어제부터 비가 내리고 있습니다.
Since yesterday, it has been raining.
In this sentence, '어제부터' introduces the point in time when a new ongoing action—reading a book—was initiated.
어제부터 새로운 책을 읽기 시작했어요.
Since yesterday, I started reading a new book.
Here, '어제부터' outlines the beginning of a subjective state—feeling strange—that started yesterday and persists to the present.