1. Introduction to PHP

✅ 1. What is PHP?

PHP stands for Hypertext Preprocessor.

• It is a server-side scripting language
• Used to create dynamic websites
• Runs on the server, not in the browser

👉 Example:

<?php
echo "Hello World";
?>

👉 Output in browser:

Hello World

📌 Key Uses:

• Login systems
• Contact forms
• E-commerce websites
• CMS (WordPress, Joomla)

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✅ 2. History & Versions

• Created by Rasmus Lerdorf (1994)
• Initially called Personal Home Page
• Later evolved into a full programming language

📌 Important Versions:

• PHP 5 → OOP introduced
• PHP 7 → Faster performance 🚀
• PHP 8 → Latest features (JIT, better error handling)

👉 Current modern version: PHP 8+

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✅ 3. How PHP Works (Client vs Server)

📌 Flow:

1. User opens website in browser (Client)
2. Request goes to server
3. Server runs PHP code
4. Server sends HTML output
5. Browser displays result

👉 Diagram (simple):

Browser → Server (PHP runs) → HTML → Browser

📌 Important:

• Browser never sees PHP code
• It only sees the output (HTML)

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✅ 4. Installing XAMPP / WAMP / LAMP

To run PHP locally, you need a local server.

🔹 Options:

• XAMPP (Windows, Linux, Mac) ⭐ Recommended
• WAMP (Windows)
• LAMP (Linux)

🔹 XAMPP Installation Steps:

1. Download from: https://www.apachefriends.org
2. Install software
3. Open XAMPP Control Panel
4. Start:
   • Apache ✅
   • MySQL ✅

📁 Folder:

htdocs/

👉 Place your PHP files here

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✅ 5. Running First PHP Script

Step 1: Create file

hello.php

Step 2: Write code

<?php
echo "My First PHP Program!";
?>

Step 3: Save in:

htdocs/hello.php

Step 4: Run in browser:

http://localhost/hello.php

👉 Output:

My First PHP Program!

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✅ 6. PHP Syntax Basics

🔹 PHP Tags

<?php
// PHP code here
?>

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🔹 Echo (Print Output)

echo "Hello";
print "World";

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🔹 Variables

$name = "Aditya";
$age = 25;

📌 Rules:

• Starts with $
• Case-sensitive

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🔹 Comments

// Single line
# Single line
/* Multi-line */

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🔹 Data Types

$string = "Hello";
$int = 10;
$float = 10.5;
$bool = true;
$array = [1,2,3];

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🔹 Simple Example

<?php
$name = "Aditya";
echo "Welcome " . $name;
?>

👉 Output:

Welcome Aditya

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🎯 Summary

• PHP is a server-side language
• Used to build dynamic websites
• Runs on Apache server (XAMPP)
• Easy syntax for beginners