Korean Copula 이다 and 아니다

In Brief

Use 이에요 after a noun ending in a consonant and 예요 after a noun ending in a vowel: 학생이에요 “(someone) is a student,” but 의사예요 “(someone) is a doctor.” In formal polite speech, both become 입니다. To say “is not,” use the separate negative form 아니에요 or formal 아닙니다, usually after 이/가: 학생이 아니에요.

Overview

The Korean copula (a linking expression that identifies one thing as another) is 이다. It links a noun to the person or thing being described: 저는 학생이에요 means “I am a student.” English changes be to am, is, or are according to the subject. Korean does not make that distinction: the same polite ending can describe “I,” “you,” “he,” “she,” “it,” or “they.” Context often supplies a subject that English requires you to state.

This is an essential A1 pattern because introductions, occupations, nationalities, labels, and definitions all use it. 이다 is shown in dictionaries, but in conversation you normally hear a form carrying a speech-level ending, especially 이에요/예요. These forms are polite enough for ordinary interactions without sounding highly ceremonial.

The negative counterpart is 아니다, “not be.” It behaves differently from the positive copula in an important way: positive 이다 attaches directly to the preceding noun, whereas 아니다 is written separately. The noun before 아니다 commonly takes the subject particle 이/가 (a small marker showing what is being identified or denied): 의사가 아니에요, “(someone) is not a doctor.”

How It Works

The beginner rule: 이에요 or 예요

First look at the final written syllable of the noun. A final consonant, often called 받침 in Korean, is a consonant pronounced at the bottom of the last Hangul block.

Noun ending	Polite form	Pattern	Example
Final consonant (받침)	이에요	noun + 이에요	학생 + 이에요 → 학생이에요
Vowel (no 받침)	예요	noun + 예요	의사 + 예요 → 의사예요

This choice depends on the Korean spelling and sound at the end of the noun, not on whether the English translation uses a, an, is, or are.

• 책이에요. — It is a book. (책 ends in ㄱ.)
• 친구예요. — (They) are a friend. (친구 ends in a vowel.)
• 서울이에요. — It is Seoul. (서울 ends in ㄹ.)
• 학교예요. — It is a school. (학교 ends in a vowel.)

Korean writes the positive copula as part of the noun phrase: 학생이에요, not 학생 이에요. Think of 이에요/예요 as an ending attached to the noun, not as an independent word corresponding neatly to English is.

Formal polite statements: 입니다

Use 입니다 in formal polite speech, including presentations, announcements, customer service, interviews, and official introductions. It follows both consonant-final and vowel-final nouns, so there is no two-form choice.

Noun	Formal polite statement	English
학생	학생입니다.	(I/you/someone) am/is a student.
의사	의사입니다.	(I/you/someone) am/is a doctor.
책	책입니다.	It is a book.

입니다 also attaches directly to the noun. Its matching formal question ending is 입니까?: 학생입니까? “Are you a student?” In everyday polite conversation, speakers more often keep 이에요/예요 and use rising question intonation: 학생이에요?

Making the negative with 아니다

The dictionary form 아니다 becomes 아니에요 in everyday polite speech and 아닙니다 in formal polite speech.

Register	Positive	Negative
Everyday polite	학생이에요	학생이 아니에요
Everyday polite	의사예요	의사가 아니에요
Formal polite	학생입니다	학생이 아닙니다
Formal polite	의사입니다	의사가 아닙니다

The full beginner pattern is:

noun + 이/가 + 아니에요

Choose 이 after a final consonant and 가 after a vowel:

• 학생이 아니에요. — (Someone) is not a student.
• 의사가 아니에요. — (Someone) is not a doctor.

Unlike the positive copula, 아니다 is a separate word: write 학생이 아니에요, not 학생이아니에요. In conversation, 이/가 may be omitted when the meaning is obvious—학생 아니에요 is common—but keeping it is a reliable neutral pattern for beginners.

Building a complete sentence

A useful basic structure is:

topic + 은/는 + identity noun + copula

The topic is what the sentence is about. 은/는 marks it: 은 follows a consonant and 는 follows a vowel.

• 저는 회사원이에요. — As for me, I am an office worker.
• 민수는 학생이에요. — Minsu is a student.
• 이것은 책입니다. — This is a book. (formal)

For a negative identity, the noun being rejected normally takes 이/가:

• 저는 의사가 아니에요. — I am not a doctor.
• 이것은 제 가방이 아니에요. — This is not my bag.

English needs an explicit subject in these sentences. Korean can omit 저는, 이것은, or another understood topic. That is why 학생이에요 can mean “I am a student,” “he is a student,” or “they are students,” depending on the conversation.

Statements and questions

Everyday polite statements and yes–no questions can have exactly the same written ending. In speech, a question normally has rising intonation; in writing, the question mark supplies the clue.

Statement	Question
한국 사람이에요. — (They) are Korean.	한국 사람이에요? — Are (they) Korean?
학생이 아니에요. — (They) are not a student.	학생이 아니에요? — Aren’t (they) a student?
책입니다. — It is a book.	책입니까? — Is it a book?

Examples in Context

Korean	English	Note
저는 학생이에요.	I am a student.	학생 has a final consonant, so use 이에요.
제 친구는 의사예요.	My friend is a doctor.	의사 ends in a vowel, so use 예요.
여기는 도서관이에요.	This place is a library.	Identifies a place.
오늘은 월요일이에요.	Today is Monday.	월요일 ends in ㄹ.
이 사람은 제 선생님이에요.	This person is my teacher.	Identifies a person and relationship.
이게 뭐예요?	What is this?	Everyday polite question; 뭐 ends in a vowel.
네, 제 우산이에요.	Yes, it is my umbrella.	The subject is understood from context.
한국 사람이 아니에요.	(I/they) am/are not Korean.	Negative identity with 이 after 사람.
저는 의사가 아니에요.	I am not a doctor.	가 follows vowel-final 의사.
이것은 책입니다.	This is a book.	Formal polite statement.
저는 김민지입니다.	I am Kim Minji.	Formal self-introduction.
여기는 출구가 아닙니다.	This is not the exit.	Formal polite negative.
민지 씨는 학생이에요?	Is Minji a student?	Rising intonation makes it a question.
아니요, 학생이 아니에요.	No, she is not a student.	아니요 is “no”; 아니에요 is “is not.”

Common Mistakes

Using 이에요 after every noun

• Wrong: 의사이에요.
• Right: 의사예요.
• Why: 의사 ends in a vowel, so it takes 예요. Reserve 이에요 for nouns with a final consonant, as in 학생이에요.

Writing 에요 instead of 예요

• Wrong: 친구에요.
• Right: 친구예요.
• Why: The standard copula spelling after a vowel is 예요. You may hear a pronunciation close to 에요 in casual speech, but write 예요.

Writing 아니예요

• Wrong: 학생이 아니예요.
• Right: 학생이 아니에요.
• Why: 아니에요 is the standard polite form of 아니다. It is a fixed form here; do not choose between 이에요 and 예요 after 아니.

Attaching the negative to the noun

• Wrong: 학생이아니에요.
• Right: 학생이 아니에요.
• Why: Positive 이다 attaches to a noun, but 아니다 is written as a separate word. The particle 이 remains attached to 학생.

Using the copula with an adjective or action verb

• Wrong: 날씨가 추워요예요.
• Right: 날씨가 추워요. — The weather is cold.
• Why: Korean descriptive verbs such as 춥다 already express “be cold.” They take verb endings directly and do not need 이에요/예요. Likewise, 가요 already means “go/goes”; do not add a copula.

Copying English number agreement

• Wrong idea: A plural subject requires a special Korean form corresponding to English are.
• Right: 저는 학생이에요 and 저희는 학생이에요 can both use 이에요.
• Why: The Korean copula does not change for first, second, or third person, or for singular versus plural. English agreement is not a useful guide here.

Usage Notes

Everyday polite versus formal polite

이에요/예요 belongs to the everyday polite style often called 해요체. It is the safest default for ordinary conversations with people you do not speak casually to. 입니다/아닙니다 belongs to a more formal style, 하십시오체. It is common in public-facing speech, workplace reports, news-like delivery, ceremonies, and especially formal first introductions.

Formal does not simply mean “more respectful in every situation.” A long friendly conversation made entirely of 입니다 forms can sound stiff or presentation-like. Conversely, 이에요/예요 remains polite and is not automatically casual.

Korean does not use an indefinite article

English often inserts a or an: “I am a student.” Korean has no direct equivalent in 저는 학생이에요. Do not try to add a word solely because English requires an article. Number words or expressions such as 한 명 “one person” are used only when quantity matters.

아니다 is not the answer “no”

Keep these two forms apart:

• 아니요 — “No,” used as a response.
• 아니에요 — “is/am/are not,” or in some contexts “No, that’s not the case / You’re welcome.”

For example, 학생이에요? — 아니요, 선생님이에요. means “Are you a student? — No, I’m a teacher.” Saying 아니에요 by itself can reject or correct an assumption, but learners should still recognize its grammatical role as a negative predicate.

Pronunciation and sound linking

When 이에요 follows a consonant-final noun, normal Korean sound linking can make the boundary less obvious than the spelling suggests. Learn the expression as a written noun plus ending, and imitate native audio rather than inserting a pause: 학생이에요 is one smooth phrase. The spelling rule remains based on the noun’s final Hangul letter.

Beyond the Basics / Advanced Use

You do not need to master the following forms at A1, but they complete the main copula system and will appear frequently.

Casual forms

With close friends, family, or younger people, the positive copula is 이야 after a consonant and 야 after a vowel. The negative is 아니야.

Noun ending	Polite	Casual
consonant: 학생	학생이에요	학생이야
vowel: 친구	친구예요	친구야
negative	학생이 아니에요	학생이 아니야

Do not use these casual forms merely because the listener is friendly. Korean speech level reflects the relationship and agreed style between speakers.

Past forms

The polite past form is 이었어요 after a consonant and usually 였어요 after a vowel. The negative past is 아니었어요.

• 작년에는 학생이었어요. — I was a student last year.
• 여기는 카페였어요. — This place used to be a café.
• 제 것이 아니었어요. — It was not mine.

Formal past forms include 이었습니다/였습니다 and 아니었습니다. These patterns show that the copula can carry tense just as other Korean predicates do.

Attributive forms: 인 and 아닌

When the identity expression modifies a following noun rather than finishing the sentence, 이다 becomes 인, and 아니다 becomes 아닌:

• 학생인 사람 — a person who is a student
• 학생이 아닌 사람 — a person who is not a student
• 한국인 친구 — a friend who is Korean / a Korean friend

This is a later noun-modifying pattern. For now, notice that you cannot place sentence-final 이에요 directly before another noun.

Written plain style and quotations

In definitions, essays, notes, and quoted clauses, you may encounter 이다 itself rather than a polite form: 고래는 포유류이다 “A whale is a mammal.” After a vowel, especially in writing, 다 may attach directly in forms such as 학교다 “It is a school.” Reported speech also uses forms such as 학생이라고 해요 “(They) say (someone) is a student” and 의사라고 해요 “(They) say (someone) is a doctor.” These belong to broader style and quotation systems, so treat them as recognition points rather than replacements for the A1 rule.

Omission in headlines and labels

Signs, labels, profiles, and headlines often present a noun without an overt copula because the identifying relationship is obvious. A form field might simply show 직업: 학생 “Occupation: student.” This does not make 이다 optional in every complete spoken sentence; it is a compact style used where the layout supplies the connection.

Practice Tips

1. Sort nouns by their last syllable. Make two short lists: consonant-final nouns such as 학생, 책, 사람 and vowel-final nouns such as 의사, 친구, 학교. Say each with the correct polite copula, then switch every item to 입니다.
2. Practice correction pairs. Say one positive and one negative sentence about the same noun: 학생이에요 → 학생이 아니에요, 의사예요 → 의사가 아니에요. This trains both the spacing and the 이/가 choice.
3. Record a three-line introduction. State your name, nationality or hometown, and occupation using 이에요/예요. Then make a formal version with 입니다. Listen for smooth attachment with no pause before the copula.

Related Concepts

• Prerequisite: Polite Ending -아/어요 — provides the everyday polite speech level used by 이에요/예요 and 아니에요.