There are 3 kinds of users. 
1. Customer
    - Register by entering his information (name, email, …).
    - Log in using Email & Password.
    - Browse products by their category or name.
    - Sort the products in any category by rate, name, and price.
    - Add product to his cart if this is available with custom quantity.
    - Checkout of products in the cart.
    - Add rate and comment for any product or seller. 
    - Edit profile information.
    - Type comments to admin.
2. Seller
    - Register by entering his information (name, email, …).
    - Log in using Email & Password.
    - Add a new product and determine its details (name, category, quantity, price, …).
    - Edit product information.
    - remove any product that he sold 
    - The seller can view his history wallet and total profit.
    - Show his feedback page.
    - The seller can search for any product by its name.
    - Edit profile information.
    - Type comments to admin.
3. Admin
    - Delete any Customer.
    - Delete any Seller.
    - Delete any product.
    - Read comments from users.

- MVC model.
- Qt FrameWork (GUI).

- V 1.0.0
- V 1.1.0
    a. admin page that can delete any customer, seller, or product.
    b. any user can type comments for admin.

- C++

- unordered_map
- vector
- stack
- array

The UI contains mainly 8 forms (Views):
1. Register new users ( customers, sellers )
2. Login for normal users ( customers, sellers )
3. Home page
    - Categories
    - Products list
4. Product page
    - Home
    - Feedback
5. Customer profile
    - Home
    - Cart
    - Favorite
    - Edit profile
6. Seller profile
    - Home
    - Available
    - Wallet History
    - Feedback
    - Edit profile
    - Add product
7. Seller view profile for customers
    - Home
    - Available
    - Feedback
8. Admin page
    - Home
    - Customers
    - Sellers
    - Feedback