이/가 - The Subject Particle
이 and 가 are particles used to mark the subject of a Korean sentence.
The subject is the person or thing that performs an action, has a particular quality, or exists in a certain place.
- 고양이가 있어요.
There is a cat. - 날씨가 좋아요.
The weather is nice. - 민수 씨가 공부해요.
Minsu studies.
Particles attach directly to nouns and show the role of those nouns in a sentence.
이 or 가?
The form depends on whether the noun ends in a final consonant or a vowel.
Use 이 after a final consonant
Noun + 이
- 학생 + 이 → 학생이
student - 책 + 이 → 책이
book - 사람 + 이 → 사람이
person
Use 가 after a vowel
Noun + 가
- 친구 + 가 → 친구가
friend - 학교 + 가 → 학교가
school - 의사 + 가 → 의사가
doctor
Basic Sentence Structure
A common Korean sentence follows this structure:
Noun + 이/가 + Verb or Adjective
The noun followed by 이/가 is the subject of the sentence.
- 고양이가 자요.
Literal: The cat sleeps.
Natural: The cat is sleeping.
- 날씨가 추워요.
Literal: The weather is cold.
Natural: It is cold.
- 친구가 한국어를 공부해요.
Literal: My friend Korean studies.
Natural: My friend studies Korean.
The literal translation helps you see the Korean sentence structure. The natural translation shows how the same meaning is normally expressed in English.
Identifying the Subject
이/가 is often used when identifying who or what performs an action.
- 민수 씨가 요리해요.
Minsu cooks. - 친구가 전화해요.
My friend calls. - 아기가 자요.
The baby is sleeping.
In these sentences, 민수 씨, 친구, and 아기 are the subjects performing the actions.
Describing Someone or Something
이/가 is also used when describing the condition or quality of a person or thing.
- 날씨가 좋아요.
The weather is nice. - 한국 음식이 맛있어요.
Korean food is delicious. - 이 가방이 비싸요.
This bag is expensive. - 제 방이 작아요.
My room is small.
In Korean, descriptive words such as 좋아요, 맛있어요, 비싸요, and 작아요 commonly follow a subject marked with 이/가.
Expressing Existence
이/가 is commonly used with 있어요 and 없어요.
- 책이 있어요.
There is a book.
I have a book. - 고양이가 있어요.
There is a cat.
I have a cat. - 시간이 없어요.
There is no time.
I do not have time. - 친구가 없어요.
I do not have a friend.
There is no friend.
The exact English translation depends on the context.
Presenting New Information
이/가 is often used when introducing new information or answering a question about who or what is involved.
- 누가 학생이에요?
Who is a student? - 민수 씨가 학생이에요.
Minsu is the student. - 누가 왔어요?
Who came? - 친구가 왔어요.
My friend came.
In these answers, 이/가 identifies the specific person being asked about.
Using 이/가 in Questions
Question words such as 누구, 뭐, and 어디 are often followed by 이/가 when they are the subject.
- 누가 선생님이에요?
Who is the teacher? - 뭐가 맛있어요?
What is delicious? - 어디가 좋아요?
Which place is good?
When answering, the person or thing that replaces the question word is also commonly marked with 이/가.
- 누가 선생님이에요?
Who is the teacher? - 수진 씨가 선생님이에요.
Sujin is the teacher.
More Examples
- 학생이 많아요.
There are many students. - 사과가 맛있어요.
The apple is delicious. - 제 동생이 운동해요.
My younger sibling exercises. - 버스가 와요.
The bus is coming. - 한국어가 재미있어요.
Korean is interesting. - 문제가 어려워요.
The problem is difficult.
은/는 and 이/가
Both 은/는 and 이/가 attach to nouns, but they have different functions.
- 은/는 introduces or contrasts the topic of a sentence.
- 이/가 identifies or focuses on the subject.
Compare the following sentences:
- 저는 학생이에요.
As for me, I am a student. - 제가 학생이에요.
I am the student.
I am the one who is a student.
Another example:
- 한국어는 재미있어요.
As for Korean, it is interesting. - 한국어가 재미있어요.
Korean is interesting.
Korean is what I find interesting.
The difference can be subtle and depends on context. For now, remember:
- 은/는 tells the listener what the sentence is about.
- 이/가 identifies who or what is the subject.
Special Forms: 내가, 네가, and 제가
Some pronouns change when they are combined with 가.
- 나 + 가 → 내가
I - 너 + 가 → 네가
you - 저 + 가 → 제가
I, polite form - 내가 학생이에요.
I am the student. - 네가 요리해요?
Are you cooking? - 제가 할게요.
I will do it.
Do not use 나가, 너가, or 저가 as the standard written forms in these structures.
Common Mistakes
Choosing the wrong form
Use 이 after a noun ending in a final consonant.
학생이 ✓
학생가 ✗
Use 가 after a noun ending in a vowel.
친구가 ✓
친구이 ✗
Adding a space before the particle
이 and 가 attach directly to the noun.
고양이가 있어요. ✓
고양이 가 있어요. ✗
책이 있어요. ✓
책 이 있어요. ✗
Using 이/가 after every noun
Not every noun in a sentence needs 이/가.
친구가 한국어를 공부해요. ✓
친구가 한국어가 공부가 해요. ✗
Each particle has a different role. Use 이/가 for the subject and other particles for other parts of the sentence.
Confusing 이/가 with 은/는
These particles are not always interchangeable.
- 저는 학생이에요.
I am a student. - 제가 학생이에요.
I am the student.
I am the one who is a student.
The first sentence introduces the speaker as the topic. The second sentence identifies the speaker as the particular person who is a student.
Quick Practice
Choose 이 or 가.
- 학생___ 공부해요.
- 친구___ 와요.
- 책___ 있어요.
- 날씨___ 좋아요.
- 한국 음식___ 맛있어요.
- 사람___ 많아요.
Answers
- 학생이 공부해요.
- 친구가 와요.
- 책이 있어요.
- 날씨가 좋아요.
- 한국 음식이 맛있어요.
- 사람이 많아요.
Sentence Practice
Complete each sentence with your own information.
- 제 친구가 __________.
- __________이/가 맛있어요.
- __________이/가 있어요.
- __________이/가 없어요.
- __________이/가 좋아요.
- __________이/가 공부해요.
Key Points
- Use 이 after a noun ending in a final consonant.
- Use 가 after a noun ending in a vowel.
- Attach 이/가 directly to the noun.
- 이/가 marks the subject of a sentence.
- 이/가 is commonly used with 있어요 and 없어요.
- 이/가 can identify or focus attention on a particular person or thing.
- 나, 너, and 저 become 내가, 네가, and 제가 before 가.
