Copula 이다 (to be)
The copula 이다 (to be) and its negative 아니다 (to not be)
Can use 이다/아니다 to identify and negate nouns in polite speech
Look at these examples. Can you spot the grammar pattern?
저는 학생이에요.
I am a student.
이것은 커피예요.
This is coffee.
저는 의사가 아니에요.
I am not a doctor.
여기는 어디예요?
Where is this place?
Pay attention to the highlighted parts. What do they have in common?
서술격 조사 이다 — The Copula 'to be'
Korean's copula 이다 means 'to be' and attaches directly to the noun — it is technically a particle, not a verb!
Polite informal (해요체) forms:
| Condition | Form | Example |
|---|---|---|
| After consonant | ~이에요 | 학생이에요 (is a student) |
| After vowel | ~예요 | 의사예요 (is a doctor) |
Negative: 아니다 → 아니에요
| Positive | Negative |
|---|---|
| 저는 학생이에요. (I'm a student.) | 저는 학생이 아니에요. (I'm not a student.) |
| 이것은 책이에요. (This is a book.) | 이것은 책이 아니에요. (This is not a book.) |
Key pattern — X는 Y이에요/예요:
This is the most basic identification sentence: "X is Y".
- 저는 선생님이에요. = I am a teacher.
- 이것은 커피예요. = This is coffee.
- 여기는 학교예요. = This (place) is a school.
Note: 이다 is ONLY for nouns. For adjectives, Korean uses descriptive verbs (형용사): 커요 (is big), 좋아요 (is good) — NOT *큰이에요.
Common Error Patterns
Used 이에요/예요 with an adjective instead of the adjective's own conjugation
이다 is ONLY for nouns: 학생이에요 (student). For adjectives, conjugate directly: 커요 (big), 좋아요 (good)
Used wrong copula form (이에요 after vowel or 예요 after consonant)
이에요 after consonant: 학생이에요. 예요 after vowel: 커피예요
저는 학생이에요.
I am a student.
학생 ends in consonant ㅇ, so use 이에요: 학생 + 이에요. Topic 저는 sets the context.
이것은 커피예요.
This is coffee.
커피 ends in vowel ㅣ, so use 예요: 커피 + 예요 (contracted from 이에요).
저는 의사가 아니에요.
I am not a doctor.
Negative pattern: noun + 이/가 + 아니에요. 의사 (doctor) + 가 (subject, after vowel) + 아니에요 (am not).
여기는 어디예요?
Where is this place?
여기 (here) + 는 (topic) + 어디 (where) + 예요 (is). Literally: 'As for here, where is it?'
Practice in course
Apply this grammar in A1 course exercises