です and だ
To be: polite です and casual だ
Use です for polite noun and な-adjective sentences; use だ in casual plain statements.
In plain language
です is a polite ending for saying what someone or something is. It follows a noun (“student”) or a certain kind of describing word, such as 静か (“quiet”). だ does a similar job in casual speech. Both come at the end of the sentence.
When to use it
Use です with someone you have just met, a teacher, or in most everyday polite conversations. You may hear だ among friends. でした is the polite past form, as in “was.”
How to build it
Start with who or what you are talking about. Add は (pronounced “wa”), then a noun or a な-adjective and です. For example: 私は学生です。 (“I am a student.”) Do not add だ after an い-adjective.
A basic pattern
Noun／な-adjective + です (polite) ／ だ (casual)
Examples in context
The grammar point is shown in blue in each sentence.
私は大学生です。わたしはだいがくせいです。I am a university student.
この町は静かだ。このまちはしずかだ。This town is quiet.
昨日は休みでした。きのうはやすみでした。Yesterday was a day off.
Watch for this
今日は暑いだ。 → 今日は暑い。／今日は暑いです。
い-adjectives do not take だ.
Quick practice: です and だ
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