～んです・のです

～んです and ～のです are used when you want to explain or emphasize something, or present information that the listener didn’t know. They soften statements, invite agreement, or provide a reason for why you’re saying something. The んです form attaches to plain (dictionary) forms, while のです is a more formal or written variant. In casual speech, んです is more common; のです can sound more explanatory or authoritative. Patterns differ slightly by the part of speech (verbs, adjectives, nouns), but the core idea is to present information as background or context rather than a bare assertion.