Why Do Koreans Add 요 to Sentences?
10-Second Answer
요 is the single syllable that marks polite speech (존댓말) at the end of a sentence. Attach it, and a casual sentence becomes polite; drop it, and a polite sentence becomes casual (반말). It's the fastest, most visible signal of politeness level in spoken Korean.
The On/Off Switch
| Casual (반말) | Polite (+요) | Meaning |
|---|---|---|
| 가 | 가요 | go / going |
| 먹었어 | 먹었어요 | ate |
| 고마워 | 고마워요 | thanks |
| 몰라 | 몰라요 | don't know |
This is exactly the mechanism behind pairs you've already seen across this site — 고마워 vs 고마워요, 괜찮아 vs 괜찮아요 — same word, 요 flips the politeness level.
Where 요 Sits in the Bigger Politeness System
요-attached sentences are the "polite" (해요체) level — the everyday default with strangers, coworkers, and most adults, as covered on the banmal vs jondaemal page. It sits BELOW the most formal level (합니다체, like 갑니다 instead of 가요) but ABOVE plain casual speech.
| Level | Example | Feel |
|---|---|---|
| Formal (합니다체) | 갑니다 | News, presentations, military |
| Polite (+요) | 가요 | Everyday default with most people |
| Casual (반말) | 가 | Close friends, younger people |
요 Also Softens Single Words
요 isn't only for full sentences — it attaches to standalone words to politely soften them too, which is why you've seen forms like 네요, 정말요, and 저도요 scattered across other pages on this site. A bare word + 요 is a quick, easy way to stay polite even in a short reply.
저도요!
Me too!
저도 ("me too") + 요 — polite short reply.
정말요?
Really?
정말 ("really") + 요 — the polite version of a casual 정말?
Common Mistakes
Mistake #1 — Thinking 요 alone makes something formal
요-level is POLITE, not the most formal register — 합니다체 is a separate, higher tier for very formal contexts.
Mistake #2 — Dropping 요 with people you shouldn't
Removing 요 shifts you into casual 반말 — appropriate only with close friends or people younger than you, per the banmal/jondaemal rules.
Mini Quiz
1. What does adding 요 to the end of a Korean sentence do?
2. Is 요-level (해요체) the MOST formal level of Korean speech?
3. What does 저도요! mean?
Related Knowledge
Learn Next
Time to put 요-level politeness to work in a real situation — ordering your first Korean coffee.
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Start today's study →Last updated: 2026-08-10 · Written and reviewed by a native Korean speaker.