だ
To be, Is
Structure
［な］Adjective + だ
Explanation
In many situations, だ is used like the English verb 'to be' (is, am, are). It serves to make a firm statement or declaration. As this is a plain form, it is only appropriate for casual conversations and should be avoided in polite speech.
Grammatically, だ is considered an auxiliary verb. These are special words that attach to the end of other words to add meaning. The word です functions in the same way as だ, but です is reserved for polite situations and is typically one of the first grammar points introduced to new learners.
You will always find だ immediately following a noun or a な-Adjective, which functions similarly to a noun.
- 猫だ。It is a cat.
- 公園だ。It is a park.
- 静かだ。It is quiet.
- 便利だ。It is convenient.
Caution
It is grammatically incorrect to place だ after an い-Adjective. While you can add です to an い-Adjective to make it polite, using だ is never an option.
- 安いだ。It is cheap. (Unnatural Japanese)
- 安いです。It is cheap. (Natural Japanese)
Caution
Many learners believe that だ is simply the 'casual version' of です, but this isn't quite accurate. です is a marker of polite speech. The true formal counterpart to だ is actually である, a structure we will cover later on. You will primarily encounter である in formal writing like essays and academic papers, whereas です is used to show politeness when speaking.
Examples
犬だ。
(It) is a dog.
友達だ。
(He) is a friend.
元気だ。
(I) am well.
静かだ。
It is quiet.
夢だ。
It is a dream.
嘘だ。
That is a lie.
医者だ。
(She) is a doctor.
仕事だ。
It is work.
車だ。
It is a car.
簡単だ。
It is simple.
時間だ。
It is time.
雨だ。
It is rain.
問題だ。
It is a problem.