PHP Registration & Login System

📂 Project Structure Explained

File	Purpose	Key Concept
config/server.php	The "Bridge"	Connects your PHP code to the MySQL Database (XAMPP).
auth/register.php	The "Front-Door"	The HTML form where users type their information.
backend/register_db.php	The "Officer"	Processes registration logic.
auth/login.php	The "ID Check"	HTML form for returning users.
backend/login_db.php	The "Security"	Verifies login credentials.
home/index.php	The "Private Room"	The homepage for logged-in users.
backend/error.php	The "Feedback"	Shows error messages.
css/style.css	The "Makeup"	Styling for the application.

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Core Concepts for Hackathons

1. The Superglobals ($_POST, $_SESSION)

• $_POST: Used to grab data from forms (e.g., $_POST['username']).
• $_SESSION: Used to "remember" a user across different pages. Crucial: Always put session_start(); at the very top of files that use sessions.

2. Database Connection (mysqli_connect)

Found in server.php. If your system isn't working, check these 4 things:

1. Host: Usually localhost
2. User: Usually root
3. Password: Empty "" by default in XAMPP
4. DB Name: Must match exactly what you named it in phpMyAdmin (register_db)

3. Password Security (md5)

Never store passwords as plain text! In this project, you use md5($password). While there are stronger methods (like password_hash), MD5 is a great starting point for learning.

4. Preventing Duplicates (The "Logic Check")

Before inserting a new user, you must run a SELECT query to see if the username or email already exists. If the database returns a result, you stop the registration and show an error.