Koreans use it when they are surprised or want to confirm something they heard.
Yes. "정말요 (jeongmalyo)" is polite and commonly used. You can also say "정말?" (jeongmal?) casually with friends.
You can say "Really? That's amazing!" — 정말요? 대단해요! (jeongmalyo? dae-dan-hae-yo!).
정말요? means "Really?" Surprise/reaction. 정말 (jeongmal) = really/truly, 요? (yo?) = polite question. Common when hearing unexpected news. Keeps conversation engaging.
1. Surprising news: Show surprise.
2. Confirm: Want to confirm what you heard.
3. Engage: Keep conversation lively.
Really? Wow!
Really? I'm surprised. (Formal)
Really? I can't believe it. (Casual)
Really? That's amazing!
• 진짜요? (jinjjayo?) - Really? (synonym)
• 그래요? (geuraeyo?) - Is that so?
• 대박! (daebak!) - Wow! Amazing!