The 합니다 (hap-ni-da) style
Korean has more than one polite register. The -아요/-어요 style you've been using is the everyday polite form. The -습니다/-ㅂ니다 style — called 합니다체 ('hap-ni-da' style) or deferential polite — is more formal and stiff. You hear it in news broadcasts, public announcements, business presentations, and in any setting where you want to sound respectful and crisp. The meaning is identical; only the register changes.
How to form it
Take the verb stem (the dictionary form minus -다) and look at its last letter. If the stem ends in a consonant (a 받침), add -습니다. If it ends in a vowel, add -ㅂ니다 directly under the last syllable. 먹다 (to eat) → stem 먹 (consonant) → 먹습니다. 가다 (to go) → stem 가 (vowel) → 갑니다. 하다 (to do) → 합니다. 공부하다 (to study) → 공부합니다.
The question form: -습니까 / -ㅂ니까
Replace -다 with -까 and add a question mark. 먹습니다 → 먹습니까? ('Do you eat?'). 갑니다 → 갑니까? ('Do you go?'). 학생입니다 ('I'm a student') → 학생입니까? ('Are you a student?'). The intonation also rises slightly on the final syllable.
The copula: 입니다 / 입니까
이다 ('to be') becomes 입니다 in this style — the same in pronunciation as 'imnida' you've heard a thousand times. 저는 학생입니다 = 'I am a student.' 이름이 뭡니까? = 'What is your name?' is the formal alternative to 이름이 뭐예요? Note that everyday 이에요/예요 corresponds to formal 입니다.
Side-by-side: same meaning, different register
가요 ↔ 갑니다 — 'I go.' 먹어요 ↔ 먹습니다 — 'I eat.' 공부해요 ↔ 공부합니다 — 'I study.' 저는 한국 사람이에요 ↔ 저는 한국 사람입니다 — 'I am Korean.' Same content, different register. As a learner you can default to -아요/-어요; switch to -습니다 when introducing yourself in a formal setting, in a job interview, in writing a report, or when speaking to a large audience.
Past tense in this style
Past -았/었어요 becomes -았/었습니다 (because the past-tense suffix ends in a consonant, ㅆ). 갔어요 → 갔습니다. 먹었어요 → 먹었습니다. 했어요 → 했습니다. We'll go deeper into past tense in the next lesson.
