-지

The Korean verb suffix -지 can be called an affirmative suffix, used declaratively to restate the listener's knowledge, and used interrogatively to request confirmation of known facts from another or yourself.

An unrelated suffix that merely happens to be spelled -지 is used as an auxilary in the negative construction -지 않다.

Inflection

When -지 is followed by the suffix -요, as in -지요, we usually abbreviate to -지요.

Contrastively

나는 애국자이지 민족주의자는 아닙니다.

I am a patriot, not a nationalist.

Declaratively

Declaratively, -지 is used to restate information known by the speaker, and presumed to be known by the listener.

오늘 날씨 춥죠?

It's cold out today, hey?For Canadians, s/hey/eh; for U.S. Americans, s/hey/right. }:)

  • The speaker knows the other person knows the weather is cold.

맞아요. 피자 정말 맛있죠.

That is right. Pizza really is delicious.

  • The speaker knows the listener agrees with them.

Interrogatively

In the interrogative, -지 adds a connotation suggesting that the speaker is asking for affirmation of known information.

오늘 금요일이지?

Today is Friday, right?

재미있죠?

It is fun, right?

  • The speaker believes the listener already thinks it's fun, but they are asking again just to make sure.

이게 뭐지?

(asking oneself) What is this?

  • The speaker is not directly asking anyone else, so they do not say "이게 뭐야?" or "이게 뭐예요?"

It sounds perfectly natural to form questions ending in -지 that do not use any interrogative nouns, but it sounds highly unnatural if the question is addressed to yourself. When asking yourself, use an interrogative noun.zotero broken; per howtostudykorean

Responsively

-지 is also commonly used in response to questions to add a nuance of "[answer], of course."

내일 갈 거야!?

Are you going tomorrow?

갈 거지.

Yeah, of course I'm going.

References