は vs が: topic and subject
The most famous pair of particles in Japanese, and the first place where translating from English stops working. The trick is that they answer different questions.
The core idea
Section titled “The core idea”- は marks the topic — “as for X, here’s some information.” The interesting part of the sentence comes after は.
- が marks the subject — “X is the one that did/is this.” The interesting part comes before が.
| Particle | Marks | The new information is… |
|---|---|---|
| は | the topic | after the particle |
| が | the subject | before the particle |
Side by side
Section titled “Side by side”私は学生です。 As for me, (I’m) a student. — answering “tell me about you.”
私が学生です。 I’m the student (you’re looking for). — answering “which of you is the student?”
Same words, different particle, different question being answered.
Where が is required
Section titled “Where が is required”Some patterns simply take が:
- Existence: 猫がいます。 — There’s a cat. (introducing something new)
- Likes and skills: 日本語が好きです。 — I like Japanese. (the thing liked takes が, not を)
- Question words: だれが来ますか。 — Who’s coming? (だれは is ungrammatical — a question word can’t be an established topic)
Rules of thumb
Section titled “Rules of thumb”- Introducing something for the first time → が. Talking about it afterwards → は. (昔々、おじいさんがいました。おじいさんは山へ行きました。)
- Answering “what about X?” → は. Answering “who/which?” → が.
- Contrast (“A is this, but B…”) → は on both: 犬は好きですが、猫はちょっと…
- When in doubt in plain statements about yourself, は is usually safe.
Test yourself
Section titled “Test yourself”「___が」or「___は」? — 空（そら）___ 青いですね。
空は青いですね。 — The sky is blue, isn’t it? You’re commenting on the sky as a known, shared topic. 空が青い would answer “what is blue?” or appear inside a larger sentence (空が青い日 — days when the sky is blue).