Как правильно использовать нет и не в русском

What is the difference between нет and не in Russian?

Russian has two words for “no/not,” and they never overlap. Нет does exactly two jobs: it answers a yes/no question (Это книга? — Нет) and it states that something doesn’t exist (у него нет сына). In that second role it is simply the antonym of есть — and it always pulls the following noun into the genitive. Не handles everything else: negating verbs, adjectives, and nouns in any other slot (это не книга, он не читает).

The teacher’s rule of thumb is the cleanest test: could you answer да here? If yes, use нет. Could есть fit instead? Also нет. Otherwise, не. So мы купили не бананы, а яблоки (“we bought not bananas but apples”) can never use нет — there’s no yes/no question and no есть in sight. Once you see нет as “да-opposite” or “есть-opposite,” the two particles stop blurring together.