I know that both are considered subject particles but when do you use one over the other?

  • IMO too basic for stackoverflow. learnkoreanlanguage.com/Particles.html and en.wikipedia.org/wiki/Korean_postpositions Commented Jun 21, 2016 at 18:14
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    @Mihai The entire site is about Korean. There's simply no point in a general Korean tag.
    – Mast
    Commented Jun 21, 2016 at 18:44
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    @qarma I agree it is very basic, but I still think it has it's place here. Maybe we can crowd-source the best, most concise, most easy to understand explanation here.
    – 파울울
    Commented Jun 21, 2016 at 19:07
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    I don't think this is a basic question. I am a native speaker, and I often can't explain why 은/는 is used instead of 이/가 at places.
    – Memming
    Commented Jun 21, 2016 at 19:27
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    This isn't basic at all - both have various different usages, some of which take some explanation. This site absolutely needs a good answer to this IMO. Commented Jun 21, 2016 at 20:58

4 Answers 4


은/는 mark the "topic" of a sentence, while 이/가 mark a "subject". This alone doesn't really help all that much to know when exactly to use which. For me, it really clicked when I learned longer English translations of the two:

집에 왔어
As for me, I came home.
Talking about me, I came home.

말한 거야.
It is me who said that.

Regarding you, what are you doing?

먹은 사과는 맛있었어.
As for the apple that the one who is me ate, it was tasty.

Whenever I am in doubt, I just replace both with these longer equivalents, and it usually works.

  • 2
    IMO the last example is different, because it's a dependent sentence. Commented Jun 21, 2016 at 20:04
  • @qarma Not 100% sure about that one either, but I wanted to find an example to use both in once sentence to show the difference. Got any better example?
    – 파울울
    Commented Jun 21, 2016 at 20:06

The 는 and 은 markers are "topic markers" and are used when introducing a new subject. The 가 and 이 markers are "subject markers" and are used when discussing a known topic. The difference can be subtle.

For example, "책은 재미있다" and "책이 재미있다" both translate to "this book is interesting," but the first one implies that a particular book is being discussed (perhaps different from another book that was just previously discussed), whereas the second one is where perhaps an additional statement is being made about the book that is already being discussed.

  • I'm not sure that your second paragraph agrees with my understanding. I'd think "책은 재미있다" could mean the book is interesting in comparison with something else - not a book - that was being discussed, whereas "책이 재미있다" is a plainer way of saying "the book is interesting. I also thought that 이/가 could be used to introduce new things - e.g. 한 남자가 이 마을에 살았다. – "a man lived in this town" - though that may be a slightly different example from yours. Of course I may be wrong so happy for anyone to put me right! Commented Jul 23, 2016 at 12:42
  • I think "책은 재미있다" could also just mean 'books are interesting' as a general statement...? Commented Jul 23, 2016 at 16:17
  • "책은 재미있다" is usually a general statement. We do not say it to compare one book with another.
    – Klmo
    Commented May 14, 2019 at 20:41

or is used as the following:

  1. A "subject" marker (I would call it a subjective "focus/topic" introducer.)

    • 예쁘다.
    • 내린다.
    • 어떤 사람 걷는다.
    • 종이 하얗다.
    • 어린애 생각 많다. (어린애 is the governing subject; 생각 is directly connected to 많다. I would say 생각 is the sub-subject.)
    • 좋다는데 네 왜 싫어해? (But do not say "나는 좋다는데 너는 왜 싫어해?")
  2. ((Used before 되다 or 아니다)) A "complement" marker

    • 형이 회장 되었다.
    • 우리는 친구 되었다.
    • 형은 회장 아니다.
    • 우리는 친구 아니다.
  3. An emphasizer

    1. ((Used before -고 싶다))
      • 김밥 먹고 싶어?
      • 나는 국수 먹고 싶다.
    2. ((Used as -지가))
      • 방이 더럽지 않다.
      • 나는 그 사람이 왠지 싫지 않았다. (그 사람 is the sub-subject.)
    3. ((Used right after a noun, in a specific construction))
      • 이곳 사람들 태반 글을 쓸 줄 모른다.
      • 여기에 있는 사람은 대개 어른이다.
    4. ((Used right after a certain adverb(ial)))
      • 저쪽에서 불빛이 번뜩 비쳐 왔다.
      • 네 말은 도대체 무슨 말인지 모르겠다.

or is used as the following (The role may differ depending on the context):

  1. A "topic" marker (I would call it a "focus/topic" maintainer and "focus/topic" changer.)

    • 예쁘다. (Subject: 꽃)
    • 이 음식 사람이 먹는다. (Object: 음식)
    • 우리 중 누가 성공할지 아무도 알 수 없다. (Objectival: 우리 중 누가 성공할지)
    • 집에 언제 갔어? (Adverbial: 집에)
    • 국수가 먹고 싶다. (Governing subject: 나)
    • 우리 친구가 아니다. (Governing subject: 우리)
    • 회장이 아니다. (Governing subject: 형)
  2. A marker for implicit or explicit comparison/contrast

    • 예쁘다. (Other things are not pretty.)
    • 이 음식 사람이 먹는다. (Human beings do not eat other food.)
    • 국수가 먹고 싶은데 너 김밥이 먹고 싶어?
    • 좋다는데 너 왜 싫다고 해?
    • 내가 좋다는데 너 왜 싫어해? ("I" thought that "you" also would like it, but "you" hate it.)
    • 국수가 먹고 싶다. (Others may want to eat others.)
    • 타는 말 동물이고 입으로 하는 말 언어이다.
    • 이 꽃 예쁜데 저 꽃 못생겼다.
    • 내가 글 자주 쓴다. ("I" do other things less often. / "I" do not talk so often.)
    • 우리 친구가 아니다. ("We" are strangers or enemies. / "They" are close friends.)
    • 회장이 아니다. (회장 is someone not my brother.)
  3. An emphasizer

    1. ((Used right after some connective endings))
      • 그렇게 빠르게 달리다가 사고가 날 것이다.
      • 장대비가 내리면 오랜 가뭄이 끝난다.
      • 음식을 먹더라도 지나치게 먹지 마라.
    2. ((Used right after a noun or certain adverb(ial)))
      • 우리에게도 문제 있다.
      • 아무리 바빠도 밥 먹자.
      • 손님이 올 것이니 밥을 넉넉히 해라.
      • 가끔 네가 생각난다.


  • 꽃이 예쁘다 suggests that flowers the speaker has seen are pretty, whereas 꽃은 예쁘다 indicates that the speaker thinks flowers are pretty. 꽃은 예쁘다 can also argue that flowers are pretty but (the / some of) others such as insects, houses, and people aren't, which does not mean that one kind of flower is pretty but other kinds aren't.

  • Some examples are duplicates because they are ambiguous.

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    Your understand about this grammar is great. Can I ask you a question, that the above grammar is completely written by you or from which source? If you took it from any source, can you tell me about it? Thank you!
    – Thai Trinh
    Commented Jul 11, 2019 at 9:07
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    @ThaiTrinh I consulted this standard dictionary and made all the example sentences considering the definitions. In addition, before leaving some comments and notes, I referred to this grammar book although some other books would be better. The other comments are based on my experience (knowledge).
    – Klmo
    Commented Jul 11, 2019 at 10:05
  • Thank you so much!
    – Thai Trinh
    Commented Jul 12, 2019 at 15:54

The difference between 는/은 and 가/이 finally clicked for me when it was explained in this video.

Topic marker (는/은): indicates information that has been previously mentioned or is clear from context; the topic being elaborated on.

Subject marker (가/이): indicates new information or emphasis on existing information.

I think this concept is difficult to explain/understand because it depends on context and the intent of the speaker. Also the best way to translate the difference to English is not with different words, but with different stress/intonation. (See the linked video for an example.)

  • thank you so much!
    – Thai Trinh
    Commented Jul 12, 2019 at 15:50

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