You Know / As You Can See (-잖아요)

-잖아요 is a contraction of -지 않아요 (isn't it?) but has evolved into a rhetorical expression meaning 'you know' or 'as you can see.' It's used when the speaker refers to something both parties already know: 내일 시험이잖아요 (You know tomorrow is the exam).

This expression can function as a gentle reminder, a justification, or mild reproach: 제가 말했잖아요 (I told you, didn't I?). It implies 'this is something you already know or should know.'

In casual speech, -잖아 (without 요) is very common. The form is used with all verb types: action verbs (가잖아요 — you know they're going), descriptive verbs (예쁘잖아요 — it's pretty, you know), and nouns (학생이잖아요 — they're a student, you know).