The difference between the 는 and 가 particles in Korean

Edit June 29: Wrote a small supplementary post on the subject here, so take a look at it after reading this one for a few more examples.



Most people studying Korean will eventually come to the particles 는 and 가, realize that they're not quite as clear-cut as other particles such as 에, 와, 도, 에게 and so on, and then we get a two to three-page thread on Dave's ESL Cafe or Galbijim or somewhere else, usually with little resolved. So I've decided to create a single authoritative post that should explain the matter once and for all. I hope.

Let's start with the basics. 는 becomes 은 when a consonant comes right before it, and 가 becomes 이 in the same way, but it's the same particle. That means that 나는 is correct but 나은 is not, 학생이 is correct and 학생가 is not.

Both of them introduce a subject. So what's the difference between the two? Here is the first thing you want to remember:

• In general, 가 is used when the part that comes before the particle is the most important (the part you want to know about), 는 is used when the important part comes after.

This is why you always say 누가? when you want to know who has done something. 누가 is short for 누구가 (though nobody uses the latter anymore), and you use 가 because what you want to know is who, which is the part that comes before the particle. You don't care so much about what they did, just who it is.

Naver gives the following example: 누가 아직 안 왔어? (who's still not here?) In this example too, the fact that somebody hasn't come has already been made clear, and the person asking the question wants to know who it is.

Now let's get into a bit more detail. I will be referencing the page on Naver's Korean Dictionary for general explanations and examples.

는.

It's good to generally think of 는 as loosely corresponding to the English 'as for'. It's used to bring up a subject, and then you give some detail about it.

Here's what Naver says about 는.

#1: 어떤 대상이 다른 것과 대조됨을 나타내는 보조사. - A particle that contrasts an object with something else.

Some examples will make this clear. I'll use a literal translation on purpose to explain the sentences, even if a bit awkward.

*사과는 먹어도 배는 먹지 마라. - Even if you eat apples, don't eat pears. Here 는 is used to contrast the eating of apples with the eating of pears.
*비가 많이는 오지 않았다. - No, it didn't rain so much. If you were to write it as 비가 많이 오지 않았다 it would be just a simple statement of fact that it didn't rain so much. With the particle there in the middle though the speaker is giving more detail as to the question of whether it rained a lot - did it rain a lot...? No, not so much. Not too much rain (today).

#2: 문장 속에서 어떤 대상이 화제임을 나타내는 보조사. - A particle that shows that an object is the subject (of a sentence).

* 나는 학생이다. - I am a student. (As for me, student)
* 편지는 “안녕하세요”로 시작했다. - The letter began with "hello". (the letter is the subject, then you give some detail about what kind of letter)

#3: 강조의 뜻을 나타내는 보조사. - A particle that gives extra emphasis.

* 아무리 바쁘더라도 식사는 해야지. - No matter how busy you are, you have to eat. (as for eating, it's something you have to do! - Not "eating is the thing you have to do" - that would be emphasizing that the person has to do something and that something is eating, but here it emphasizes that there's something called eating, and you have to do it. Not necessarily anything else.)
* 놀러 가더라도 멀리는 가지 마라. - (Even) If you go play, don't go far. (As for going far, don't do that.)


Now let's contrast that with 가.

가.

As explained above, this places a larger emphasis on the part that comes before the particle. You are more concerned with who did what than what they did, more concerned with what went than how something went, and so on. Let's see what Naver has to say.

#1: ...Naver doesn't really define the first meaning well so I won't include it here. Basically it's to emphasize the part that comes before the particle, or something you are directly experiencing. Luckily there are a ton of examples.

* “누가 이 시를 썼느냐?” “언니가 썼습니다.” - Who wrote this poem? (Older) sister wrote it. (Both times what's important is who did the writing, not the act of writing itself. We already know that a poem has been written)
* 오늘은 날씨가 덥다. - It's hot today. (The subject has already been introduced with so we're going to talk about today. Then you use 가 to describe the weather. If you used 는 after 날씨 it would be like you were going to start a new sentence.)
* 우리가 이기는 것은 분명하다. 다만 어떻게 이기느냐가 문제다. - It's clear that we're just to win. The only issue is how we're going to win. (The first one emphasizes that we're going to be doing the winning, the next one shows that how the winning is going to be done is the important part)
* 오늘은 10번에서 15번까지가 청소 당번이다. - Numbers 10 to 15 are doing the cleaning today. (Somebody's already doing the cleaning, and the one's that are going to do it are #10 - #15)

#2: ‘되다’, ‘아니다’ 앞에 쓰여｝ 바뀌게 되는 대상이나 부정(否定)하는 대상임을 나타내는 격 조사. - Used in front of ‘되다’ and ‘아니다’. Shows a changing object, or shows that it is negative.

This is a completely different use from the one above (emphasis), so take special note of this. This is a part that confuses a lot of people because 가 isn't always just used to emphasize the part that comes before.

If you know Japanese, take note that this in the first case corresponds to Japanese に in になる.

* 올챙이가 개구리가 되었다. - The tadpole became a frog. (used because we have the verb 되다)
* 고래는 물고기가 아니다. - Whales aren't fish. (used because it's a negative 아니다)

And finally:

#3: 앞말을 지정하여 강조하는 뜻을 나타내는 보조사. 흔히 뒤에는 부정적인 표현이 온다. 연결 어미 ‘-지’ 뒤에 오는 ‘가’는 ‘를’이나 ‘ㄹ’로 바뀔 수 있다. - A particle that designates and gives emphasis to the word before it. Often followed by a negative. When you have 지 you can turn the 가 into 를 or ㄹ.

What? Again, some examples should show what this part is talking about.

* 방이 깨끗하지가 않다. - the room's not clean. (Why doesn't it say 방은? That's because if you do that it sounds like you're going to start talking about the room in some detail. You want to make it short. Then the next 가 emphasizes the 깨끗하지 않다 - it's not clean.)
* 동네에 남은 사람은 거의가 노인이다. - The people left in the town were almost all elderly.
* 나는 김치가 먹고 싶었다. - I wanted to eat kimchi. (Kimchi's what I wanted to eat)
* 나는 학교가 가고 싶다. - I want to go to school. 가 is used here to emphasize that school is person's want. (School is what I want to go (to)!) With the general 로 directional particle it would just be a statement of fact.



This post probably won't clear up every single problem with the two particles but hopefully it should serve as a good foundation for the difference between the two. Try also doing searches on Google with the words in parenthesis to see what comes up. Armed with a bit of knowledge from here and going through a good number of examples you should be able to see the difference between the two.