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@@ -34,6 +34,19 @@ Journi is a web application for journaling and visualizing travel experiences. U
 
 ---
 
+## Backend — Firebase
+
+![Database diagram](/DB-diagram.PNG)
+
+| Service | Purpose |
+|---------|---------|
+| **Authentication** | Google account sign-in via `GoogleAuthProvider` |
+| **Firestore** | Stores user profiles (`users/{uid}`) and journal entries (`users/{uid}/entries/{id}`) |
+| **Storage** | Stores uploaded trip photos, accessed per user |
+| **Security rules** | Simple per-user access — only authenticated users can read/write their own data |
+
+---
+
 ## Code Organization
 
 ```
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