In this episode, we'll learn subject markers. Subject markers are used to tell which noun is the subject in the sentence.
이 and 가 are most widely used subject markers in Korean.
동생 친구들이 집에 놀러 왔다.
My younger sister's friends came to my home to play.
There are a few things that you should be careful:
First of all, when 이/가 is used with other markers. It is used in the back.
그것이만 전부가 아니다. (x)
그것만이 전부가 아니다. (o)
That is not the everything.
여기가까지 우리 조가 해야 할 일이야. (x)
여기까지가 우리 조가 해야 할 일이야. (o)
The thing that we should finish is until here.
Second, 이/가 cannot work together with 은/는, 도.
그 옷이는 너무 비싸요. (x)
그 옷은 너무 비싸요. (o)
That clothes is too expensive.
나도가 한국어 공부 중이야. (x)
나도 한국어 공부 중이야. (o)
I'm studying Korean, too.
Third, when 나(I) and 저(polite I) meet 가, they become "내가" and "제가" each. And 누구(who) become 누가.
Who will do this?
I'll do it.
Finally, when 이 and 가 are used with 되다 and 아니다, the noun in front of 이/가 is not a subject. It's a complement for those verbs. It shows what they became and what they are not.
그 아이는 만화가가 되었다.
That kid became a cartoonist.
저는 학생이 아닙니다.
I'm not a student.
께서 is used when you want to respect the subject.
할머니께서 말씀하시니 잠깐 조용히 해 줄래?
Grandma is talking. Can you be quiet?
이번 행사를 위해 박 의원님께서 많이 도와 주셨습니다.
For this event, congressman Park helped a lot for us.
One thing you should be careful is that you must use "시" in the verb form when you use 께서. If not, it is really awkward.
Usually, 에서 is used for places. However, if the subject is an organization like 학교(school), 회사(company), 모임(get-together), 정부(government), 에서 is used for the subject.
회사에서 연말에 보너스를 준다고 합니다.
It is said that our company will give us a bonus at the end of the year.
정부에서 그러라고 하긴 했는데, 그럼 우리는 완전 파산하거든? 어쩌지?
The government said us to do so, but if we do that, we'll go out of business. What should we do?
Maybe, some of you might have wondered where is 은/는. 은/는 are not subject markers. They are auxiliary makers. So, I didn't cover them here. I've covered the detailed difference between 은/는 and 이/가 before. Please check the link in the website.