이다: The Korean Verb 'To Be' for Nouns

Every Korean sentence needs a verb at the end. When what you want to say is “X is Y” and Y is a noun, that verb is 이다.

It is the first thing you can build a whole sentence with, and it behaves unlike anything in English.

It is an ending, not a word

This is the part to get right immediately.

English is is a separate word: “I is a student.” Korean 이다 is glued to the noun:

저는 학생이에요.     ✅
저는 학생 이에요.    ❌  (space — wrong)

No space. Ever. A Korean reader sees the spaced version the way you would see “student is” written as “studentis” — it registers as an error before they finish reading.

Choosing the form

Look at the last letter of the noun, not at the meaning.

Ends in a consonant → 이에요
Ends in a vowel → 예요

학생 (ends in ㅇ, a consonant)  →  학생이에요
가수 (ends in ㅜ, a vowel)      →  가수예요

That is the whole rule. 예요 is simply 이에요 contracted — the 이 gets absorbed after a vowel because 가수이에요 is awkward to say quickly.

The pattern is the same one behind 은/는 vs 이/가 (은 after consonants, 는 after vowels) and 을/를. Korean does this constantly: pick the form that is easier to pronounce after what came before.

The formal version

-입니다 covers both cases — no consonant/vowel choice at all.

Use 입니다 in a presentation, a job interview, or a news broadcast. Use 이에요/예요 everywhere else. See -습니다, -습니까 for when each fits.

The trap: 이다 vs 있다

English uses is for two completely different ideas, and Korean does not.

이다 — identity. X is Y.
있다 — existence. X exists / there is X.

학생이에요.      I'm a student.        (identity)
학생 있어요?     Is there a student?   (existence)

Also:

• 여기가 우리 학교예요 — This is our school. (it is that thing)
• 여기에 학교가 있어요 — There’s a school here. (it exists here)

Learners coming from English reach for 있다 when they mean 이다 constantly, because English gave them no reason to separate the two. Once you hear the difference it stops being difficult.

Making it negative

You cannot put 안 in front of 이다. It has its own dedicated negative word: 아니다.

저는 학생이에요. — I’m a student.
저는 학생이 아니에요. — I’m not a student.

Notice that the particle changes too — 학생이 아니에요, not 학생을. That is covered in 이/가 아니다.

Past tense

• 학생이었어요 — I was a student.
• 가수였어요 — I was a singer.

Same consonant/vowel split, one layer deeper.

Putting it together

저는 폴이에요. — I’m Paul.
제 이름은 폴이에요. — My name is Paul.
저는 한국 사람이 아니에요. — I’m not Korean.

Three sentences, and you can already introduce yourself. That is why this ending comes first.