だ / です (da / desu)
だ / です — “A is B”
Pattern
-
名詞 ＋ ですPolite: Noun + です (e.g. 学生です) -
名詞 ＋ だPlain: Noun + だ (e.g. 日曜日だ)
What it does
Japanese does not use a verb like “be” in the same way as English. Instead, you put です (polite) or だ (plain) after a noun to say what something is: これは本です, 今日は日曜日だ. It is often paired with は, which marks the topic.
Polite or plain?
Use です with teachers, strangers, customers and in most everyday polite speech. Use だ with close friends and family, in diaries, and inside longer sentences written in plain style. The meaning is the same; only the level of politeness changes.
Good to know
The negative is ではありません／じゃありません (polite) and ではない／じゃない (plain); the past is でした (polite) and だった (plain). In plain speech, the final だ is often dropped or replaced by particles such as ね and よ, and men tend to use だ more directly than women do.
Examples
-
これは本（ほん）です。
Kore wa hon desu.
This is a book.
Noun + です is the basic polite “A is B” sentence.
-
私（わたし）は学生（がくせい）です。
Watashi wa gakusei desu.
I am a student.
は marks the topic “I”; です says what I am.
-
今日（きょう）は日曜日（にちようび）だ。
Kyō wa nichiyōbi da.
Today is Sunday.
だ is the plain form; the meaning is the same as 日曜日です.
Common mistakes
- です and だ attach to nouns and na-adjective stems, not directly to verbs. Do not say 食べるです; say 食べます or 食べる. (For i-adjectives, 高いです is fine, but 高いだ is not.)
- Do not use だ when speaking politely to a teacher or a stranger; choose です.
More grammar points
- でも でも — “but / however” at the start of a sentence
- どんな どんな～ — “what kind of ～”
- どうやって どうやって～ — asking “how / by what means”
- があります ～があります — “there is ～” (things)
- がほしい ～がほしい — “I want ～”
- がいます ～がいます — “there is ～” (people and animals)
- い-adjectives い-adjectives — adjectives ending in ～い
- 一緒（いっしょ）に 一緒に～ — “together (with)”
- じゃない・ではない ～じゃない / ～ではない — the negative of だ and です
- か～か A か B — “A or B”
- けど ～けど — casual “but / although”
- けれども ～けれども — a polite “but / although”
- な-adjectives な-adjectives — take な before a noun
- なる ～になる — “to become ～”
- んです ～んです — explaining the situation
- に行（い）く ～に行く — “go to do ～”
- にする ～にする — deciding on / choosing something
- のです ～のです — the explaining ending (casual: ～んです)
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