Exercise 3: Matching Firebase Products to Later Chapters — Possible Solution
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THE FOUR PRODUCTS AND THEIR CHAPTERS
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1. Firestore (the NoSQL document database) - covered in depth in Chapter 2, Data Modeling in Firestore.
2. Cloud Functions (serverless backend functions) - covered in Chapter 3 (Barcode Lookup via a Cloud Function) and again in Chapter 10 (Recipe Lookup with TheMealDB), the two places this app genuinely needs server-side code.
3. Firestore Security Rules (declarative access-control rules) - covered in Chapter 6, once the app starts writing directly to the database from the browser.
4. Firebase Authentication (managed sign-in and user accounts) - covered in Chapter 11.

(Firebase Hosting, also mentioned in this chapter for completeness, is covered in Chapter 12 on deployment.)

WHY THIS WORKS AS AN ANSWER
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It correctly names all four products this chapter previews and correctly matches each to the specific later chapter (or chapters, in the case of Cloud Functions) where that product is actually covered in depth, rather than just listing the products without their corresponding chapters.