Web applications are usually divided into two parts: frontend and backend.

The frontend is everything you see and interact with in your browser.

For example:

• Buttons;
• Forms;
• Text and images.

This is the visual part of an application.

The backend is everything that happens behind the scenes.

It is responsible for:

• Processing data;
• Handling logic;
• Storing and retrieving information.

Users don't see the backend, but it powers the application.

Imagine a login form.

• You enter your email and password;
• The frontend sends this data to the backend;
• The backend checks if the data is correct;
• The result is sent back to the frontend;
• You are logged in (or see an error).

How They Work Together

Frontend and backend are always connected:

1. Frontend → sends data;
2. Backend → processes it;
3. Backend → sends result;
4. Frontend → shows it.