「は」marks the topic of the sentence — the thing you are talking about. Structure: Noun ＋ は ＋ predicate ✅ Positive: Kore wa hon desu. (This is a book.) ❌ Negative: Kore wa hon dewa arimasen. (This is not a book.) ❓ Question: Kore wa hon desu ka? (Is this a book?) 💡 は vs が: は＝topic marker, が＝subject / focus marker