は (wa) marks the topic, what the sentence is about, while が (ga) marks the subject when it is new information or the focus. English does this with stress and word order instead of particles. The working rule: は for things already in the conversation and for contrast, が for new information, question words, and likes, wants and abilities.
English has one slot for the subject and shows emphasis with your voice. Compare "JOHN broke the window" with "John broke the WINDOW." Same words, different focus. Japanese moves that job into the particle. The first sentence is closer to ジョンが窓を割った (Jon ga mado o watta): John, and nobody else, is the point. The second is closer to ジョンは窓を割った (Jon wa mado o watta): we are already talking about John, and the news is what he did.
So the question is never "which one is the subject?" Both can sit on the subject. The question is "is this word old information or the news?" Textbooks translate は as "as for," which sounds odd in English but captures the idea: 私は学生です (Watashi wa gakusei desu) is "As for me, I'm a student." The new information is 学生 (gakusei), student, not 私 (watashi).
| Situation | Particle | Example |
|---|---|---|
| Question word as subject | が | 誰が来ましたか (Dare ga kimashita ka): Who came? |
| Answering that question | が | 田中さんが来ました (Tanaka-san ga kimashita): Tanaka came. |
| Something just noticed | が | あ、猫がいる (A, neko ga iru): Oh, there's a cat. |
| Talking about it after that | は | その猫は黒い (Sono neko wa kuroi): That cat is black. |
| Inside a relative clause | が | 私が作ったケーキ (watashi ga tsukutta kēki): the cake I made |
| Contrast | は | 肉は食べますが、魚は食べません (Niku wa tabemasu ga, sakana wa tabemasen): Meat I eat, but fish I don't. |
The first row is the most reliable rule in the whole topic: a question word such as 誰 (dare, who), 何 (nani, what) or どれ (dore, which one) can never take は. "Dare wa kimashita ka" is simply wrong. Because the question word is the unknown, the answer to it is the news, so the answer takes が too.
This is the mistake English speakers make most, because English treats the liked thing as an object. "I like sushi" has sushi as the object of "like," so learners reach for the object particle を (o) and say 寿司を好きです. The standard sentence is 私は寿司が好きです (Watashi wa sushi ga suki desu). In Japanese, 好き (suki) is not a verb but an adjective, closer to "As for me, sushi is likable."
The same pattern covers a small group of very common words:
The person who likes, wants or can do the thing gets は, and the thing itself gets が. That gives you the two-particle sentence that looks strange at first and soon becomes automatic.
The classic example is 象は鼻が長い (Zō wa hana ga nagai). Word for word it is "As for elephants, the nose is long," and it means "Elephants have long trunks." English has to restructure the sentence with "have," but Japanese stacks a topic and a subject. You will use this pattern every day without noticing:
If you try to translate "I have a headache" with the verb "have," you end up with something no one says. Think of the topic as the frame and the が phrase as the description inside it.
When a word becomes the topic, は takes the place of が or を: 肉を食べます (niku o tabemasu) becomes 肉は食べます (niku wa tabemasu) when you are contrasting meat with something else. You never write "o wa" or "ga wa." With other particles, は is added after them: 東京には (Tōkyō ni wa), 日本では (Nihon de wa), 友達とは (tomodachi to wa).
That contrast effect is why は shows up so often in negative answers. Ask 肉を食べますか (Niku o tabemasu ka), "Do you eat meat?", and a vegetarian may answer 肉は食べません (Niku wa tabemasen). The は quietly says "meat, no, though other things are fine." English speakers sometimes miss this hint, so listen for it: a single は where you expected を often means "this one, at least."
私は田中です (Watashi wa Tanaka desu) is how you introduce yourself. 私が田中です (Watashi ga Tanaka desu) means "I'm the one who is Tanaka," the right answer when someone walks into a room and asks 田中さんはどなたですか (Tanaka-san wa donata desu ka), "Which of you is Tanaka?" This is called the exhaustive use of が: it picks out one item from a group. 田中さんが社長です (Tanaka-san ga shachō desu) answers "Who is the president?" and means Tanaka, not anyone else.
A second trap: once the topic is set, Japanese drops it. English speakers tend to start every sentence with 私は, which sounds stiff and self-focused. After the first sentence, just leave it out: 田中です。大阪から来ました。 (Tanaka desu. Ōsaka kara kimashita.)
A quick test for any sentence: what question does it answer? If it answers "What about X?", X takes は. If it answers "Who?" or "What?", the answer takes が. Then say the pairs out loud, a question and its answer, because the choice gets faster when your ear expects it. Practicing short exchanges with a tutor such as Polly in PollyStop, or with a patient friend, builds that reflex faster than filling gaps on paper.
It is a historical spelling. Centuries ago the sound of this kana shifted to wa in positions like the particle, and when spelling was reformed, the particle kept its old spelling. Everywhere else, は is read ha, as in はな (hana), flower.
Usually, but with words like 好き (suki), 分かる (wakaru) and 欲しい (hoshii), が marks what an English speaker would call the object: the thing liked, understood or wanted. The person goes with は.
In casual speech, Japanese speakers often drop は and が, as in これ、おいしい (Kore, oishii), This is tasty. In polite speech and in writing, keep them, and as a learner it is better to choose one than to hide the choice.
Learn the fixed cases first: question words and their answers take が, likes and abilities take が, relative clauses take が. Default to は for the topic you are talking about, and notice contrast whenever は replaces を.
