Learn Hardcore Korean: jeodo donguihaeyo.

도 is the additive particle meaning also/too/as well. It attaches directly to the noun or pronoun and replaces whatever case/topic marker would otherwise be there.
So 저도 means “I, too.” You do not stack 도 with 은/는 or 이/가. Don’t say 저는도 or 저가도. Just use 저도.

What’s the difference between 저도 and 나도?

저도 uses the humble pronoun 저 and is used in polite or formal situations (with -요 or -습니다 endings).
나도 uses the plain pronoun 나 and is for casual speech with friends or younger people (with -어/아 endings).
Keep levels consistent:
- Polite: 저도 동의해요.
- Casual: 나도 동의해.
- Formal: 저도 동의합니다. Avoid mixing like 나도 동의해요 in careful speech.

How is 동의해요 formed? What’s the dictionary form?

The dictionary form is 동의하다 (a 하다-verb built from the Sino-Korean noun 동의 + 하다).
In the polite present, 하다 → 해요, so 동의하다 → 동의해요.
Other common forms:
- Formal: 동의합니다
- Past: 동의했어요 / 동의했습니다
- Asking politely: 동의해요? / 동의하세요?

Is 동의해요 the most natural way to agree, or should I say something else in everyday talk?

동의해요 is perfectly fine, but it can sound a bit formal or “discussion/meeting-like” in casual chat.
Very common everyday equivalents:
- 맞아요. (That’s right.)
- 그래요. / 그렇죠. (Right / That’s so.)
- 저도 그렇게 생각해요. (I think so too.)
- 동감이에요. (I feel the same.)
For voting/supporting a proposal, 찬성해요 can be more precise than 동의해요.

Can I just say 저도요?

Yes. 저도요 is an elliptical “Me too” that repeats the previous predicate in context.
It’s great in conversation when it’s clear what you’re agreeing with. In writing or when clarity matters, the full 저도 동의해요 is safer.

How do I say “I agree with that opinion/with you” more explicitly?

동의하다 typically takes 에 with the thing you agree with:
- 그 의견에 동의해요. (I agree with that opinion.)
- 선생님 말씀에 동의해요. (I agree with what you said, teacher.)
Don’t use 을/를 with 동의하다 for the opinion: not 의견을 동의해요.
For a person, Korean often refers to their words/thoughts instead of the person directly:
- Instead of “I agree with you,” say 말씀에 동의해요, 생각에 동의해요, or simply 저도 그래요.

How is “의” pronounced in 동의해요?

In careful speech, 동의 is pronounced roughly [dong-ui].
In everyday speech, 의 in this position often reduces to [i], so you’ll hear 동의해요 as [dong-i-hae-yo].
The particle 의 (’s) is usually pronounced [e], but that’s a different use.

What about spacing? Is it 동의 해요 or 동의해요?

Write it as one word: 동의해요. The verbal noun + 하다 compounds are written together, and conjugations attach to that.
Particles attach without a space: 저도 동의해요, not 저 도 동의 해요.

Can I move 도 somewhere else, like 동의도 해요?

저도 동의해요 emphasizes “I, too.”
동의도 해요 is grammatical but different: it means “I also agree (among other things I do),” focusing on the action “agree” as another item in a list. Use it only when that nuance fits.
Don’t put 도 on the verb ending (e.g., not “동의해요도”).

How do I negate it? What’s the nuance with 도 in negatives?

Standard negative: 동의하지 않아요.
Colloquial: 동의 안 해요.
With 도:
- 저도 동의하지 않아요. = I also don’t agree (someone else already said they don’t).
- 저는 동의하지 않아요. = I don’t agree (no “also” implication).

How do I ask “Do you agree (too)?” politely?

Neutral polite: 동의해요?
With subject honorific for the listener: 동의하세요?
Formal: 동의하십니까?
To include “too,” add 도 to the appropriate noun: e.g., 선생님도 동의하세요? (Do you also agree?)

Is it okay to use 당신 to say “I agree with you”?

Generally avoid 당신 in everyday Korean; it can sound rude or unnatural.
Prefer titles/names plus their words/thoughts:
- 선생님 말씀에 동의해요.
- Or just 저도 그래요 / 저도 동의해요 when context is clear.

When should I use 찬성하다 instead of 동의하다?

찬성하다 = to be in favor of a plan/proposal (voting, choices). Example: 그 안에 찬성해요.
동의하다 = to agree/consent to an idea or statement. Example: 그 의견에 동의해요.
In many discussions they overlap, but 찬성 feels more like supporting a motion; 동의 is agreeing with a claim/point or giving consent.

Is there any legal or formal nuance to 동의하다 I should know?

Yes. 동의 often means “consent” in legal/administrative contexts:
- 개인정보 수집에 동의합니다. (I consent to the collection of personal information.)
In casual talk it’s still fine for “agree,” but be aware of that formal shade.

Can I add emphasis like “I also definitely agree”?

You can add adverbs:
- 저도 정말 동의해요.
- 저도 완전히 동의해요.
Or use 역시 for “as expected/also”: 저도 역시 동의해요. (Slightly more nuanced than plain 도.)

Is “저도 동의해요, especially about X” okay? How do I continue naturally?

Yes. Natural continuations:
- 저도 동의해요. 특히 X 부분이요.
- 저도 동의해요. 다만 Y는 좀 다른데요… (I agree, but Y is a bit different…)
A brief pause or sentence break is common when adding specifics or softening with a contrast.