User Interface: The app will have a user-friendly interface designed with HTML and CSS, allowing users to interact with the app easily. It may include sections for the shopping list, input fields to add items, buttons for actions (add, remove, mark as purchased, etc.), and possibly a login/registration area.

Firebase Integration: The app is integrated with Firebase, which acts as the backend database. Firebase Realtime Database is commonly used to store and synchronize shopping list data across multiple users and devices in real-time.

Adding and Managing Items: Users can add items to their shopping list by typing them into an input field and clicking an "Add" button. The added items will then be displayed in the shopping list section. Users may also be able to mark items as purchased or remove them from the list.

Real-time Updates: Whenever a user adds, removes, or updates an item, the changes are immediately synced with the Firebase database, and all other users viewing the same shopping list will see the changes in real-time without needing to refresh the page.