Almost every learner meets Korean politeness as one ladder: 합니다 at the top, 해요 in the middle, 해 at the bottom. Pick a rung and stay on it.
That model is wrong, and it breaks the first time you talk to a friend about your teacher.
1 · The two dials
| Dial | Raises | Shown by |
|---|---|---|
| Listener | The person you are talking **to** | The sentence ending: 합니다 · 해요 · 해 |
| Subject | The person you are talking **about** | -(으)시- inside the verb, and honorific nouns |
| Korean | To whom | About whom |
|---|---|---|
| 선생님이 가셨습니다 | Someone senior | The teacher — raised |
| 선생님이 가셨어요 | A polite everyday listener | The teacher — raised |
| 선생님이 가셨어 | A close friend | The teacher — raised |
| 친구가 갔어 | A close friend | A friend — not raised |