〜んです／のです

Meaning

Conversational んです and more written のです connect a statement to its context: ‘the thing is…’.

Formation

1. Plain verb or i-adjective + んです: 行くんです, 痛いんです.
2. Add な after a noun or na-adjective: 学生なんです, 静かなんです.
3. Use 〜んですか in a question; the full form 〜のです works the same way.

When to use it

Explaining circumstances

Gives a reason or background that helps the listener understand a situation.

Asking for an explanation

The form 〜んですか asks about a reason, intention, or further details.

Important notes

• The pattern has no single required translation; context or a phrase such as ‘the thing is’ often conveys its nuance.
• んです is the usual conversational form, while のです often sounds more written or formal.

Common mistakes

• Do not put だ before んです: use 学生なんです, not 学生だんです.
• Do not attach んです to a polite form: 行きますんです is incorrect; use plain 行くんです.

Similar grammar

• 〜かPlain 〜か neutrally asks for a fact, while 〜んですか expects context or an explanation.
• V普通形・Aい + から／N・Aな + だから〜から directly states a reason, while 〜んです presents the whole sentence as an explanation.