이/가
Subject Marker
이/가 is a particle that attaches to a noun to show it is the subject of the sentence—the one performing an action or being described.
How It Works
In Korean, particles are attached to words to indicate their grammatical function. The particle 이/가 is one of the most fundamental, as it marks the subject of a sentence.
The subject is the person, place, or thing that performs the action of the verb or is described by an adjective.
How to Choose:
- Use 이 after a noun that ends in a consonant (받침).
Example: 학생 + 이 → 학생이 (student) - Use 가 after a noun that ends in a vowel.
Example: 의사 + 가 → 의사가 (doctor)
Special Forms:
Some pronouns change form when 가 is attached:
- 나 (I, informal) + 가 → 내가
- 저 (I, formal) + 가 → 제가
- 누구 (who) + 가 → 누가
When to Use 이/가:
While both 이/가 and the topic marker 은/는 can appear on the subject, they have different nuances.
Use 이/가:
1. To identify who or what is the subject for the first time.
Example: 옛날에 공주가 살았어요. (Once upon a time, a princess lived.)
2. To emphasize the subject, often in response to a question like 'Who?' or 'What?'.
Example: 누가 만들었어요? → 제가 만들었어요. (Who made it? → I made it.)
3. For general statements of fact or descriptions.
Example: 날씨가 좋아요. (The weather is good.)
Examples (5)
- 고양이가 자요.
The cat is sleeping.
Word by Word: Cat (subject) sleeps.
고양이 ends in a vowel, so 가 is used to mark it as the subject.
- 책이 재미있어요.
The book is interesting.
Word by Word: Book (subject) is interesting.
책 ends in a consonant (ㄱ), so 이 is used.
- 날씨가 좋아요.
The weather is good.
Word by Word: Weather (subject) is good.
- A: 누가 왔어요?
B: 제 친구가 왔어요.
A: Who came? B: My friend came.
가 is used to ask 'who' (누가) and to identify the specific person who came (제 친구가).
- 제가 학생입니다.
I am a student.
This uses the special form 제가 (from 저 + 가). This sentence emphasizes that 'I' (and not someone else) am the student. In a neutral introduction, '저는 학생입니다' is more common.
Common Mistakes
Using the wrong particle for the final sound.
Not Quite사람가 많아요.Better사람이 많아요.The noun 사람 ends in a consonant (ㅁ), so you must use 이, not 가.
Confusing the subject marker (이/가) with the topic marker (은/는).
Different Meaning날씨는 좋아요?Better날씨가 좋아요?When asking about or describing the current state of something, like the weather, 이/가 is more natural. '날씨는' would imply a contrast, like 'The weather is good, but...'
Using the base pronoun instead of the special form with 가.
Not Quite저 가 할게요.Better제가 할게요.The formal pronoun '저' changes to '제' when the subject particle '가' is attached. The same happens with '나' becoming '내' (내가).
Related Patterns
- 은/는Topic Marker
This is the topic marker. It is the most commonly confused particle with 이/가. While 이/가 identifies the subject, 은/는 introduces a topic or shows contrast.
- 을/를Object Marker
This is the object marker. Understanding the difference is key to sentence structure. 이/가 marks the 'doer' (subject), while 을/를 marks what the action is done 'to' (object).
- Word order basics
Particles like 이/가 are essential for understanding Korean word order. Because particles clearly mark a word's function, the word order can be more flexible than in English.
- 이다To Be
이/가 is often used to mark the subject of a sentence ending with the copula 이다 ('to be'), as in '이것이 책입니다' (This is a book).
- 이/가 / 은/는Subject vs. Topic Marker
A helpful comparison explaining when to choose subject marker vs topic marker.
Learn Next
Patterns that build on this one.