Mastering PHP: From Basics to Building Dynamic Web Applications
Chapter 2: PHP Basics & Setup
🔹 1. What Is PHP?
PHP (Hypertext Preprocessor) is a server-side
scripting language designed specifically for web development. It runs on the
server and is embedded into HTML, enabling dynamic content generation, user
interaction, database communication, and much more.
✅ Key Features:
- Open-source
and free
- Embedded
directly into HTML
- Works
across all major operating systems
- Widely
supported by web servers (Apache, Nginx)
- Integrates
easily with databases like MySQL
PHP powers over 75% of the web, including platforms like
WordPress, Drupal, and Laravel-based apps.
🔹 2. Setting Up Your
Local PHP Environment
To run PHP scripts on your computer, you need:
- A web
server (like Apache)
- The PHP
interpreter
- A database
(usually MySQL for full-stack apps)
✅ Recommended Tools:
|
Tool |
Platform |
Description |
|
XAMPP |
Windows/Linux/macOS |
Includes
Apache, PHP, MySQL, and phpMyAdmin |
|
MAMP |
macOS/Windows |
Same as
XAMPP, but macOS optimized |
|
Laragon |
Windows |
Lightweight,
fast, and portable |
✅ Installation Steps (XAMPP
Example):
- Download
XAMPP from apachefriends.org
- Install
it like any normal software
- Start
Apache and MySQL from the XAMPP Control Panel
- Place
your PHP files in htdocs folder (e.g. C:\xampp\htdocs\myapp)
- Access
your script via browser at:
http://localhost/myapp/index.php
🔹 3. Writing Your First
PHP Script
Create a file called index.php in your XAMPP htdocs folder.
<?php
echo
"Hello, PHP World!";
?>
Visit http://localhost/index.php and you’ll see the output:
Hello,
PHP World!
✅ Always start your PHP code with
<?php and close it with ?>.
🔹 4. PHP Syntax Basics
✅ Output Methods:
echo
"Welcome!"; // Most
common
print
"Welcome again!"; // Slightly slower
✅ Comments:
//
Single-line comment
#
Another single-line comment
/*
Multi-line
comment */
✅ Variables:
$name
= "Alice";
$age
= 25;
echo
"Name: $name, Age: $age";
✅ Variables start with $, are
case-sensitive, and do not require declaring types.
🔹 5. Mixing PHP and HTML
PHP can be embedded inside HTML for dynamic rendering.
<html>
<body>
<h1><?php echo "Welcome,
$name!"; ?></h1>
</body>
</html>
✅ This is how WordPress, Laravel
Blade, and other PHP-based systems render views.
🔹 6. Practical Example:
Simple Greeting Form
✅ HTML + PHP Example:
<form
method="post">
<input type="text"
name="username" placeholder="Enter name">
<input type="submit"
value="Submit">
</form>
<?php
if
($_SERVER["REQUEST_METHOD"] == "POST") {
$username = $_POST['username'];
echo "Hello, " .
htmlspecialchars($username);
}
?>
✅ This form collects user input
and safely outputs it using htmlspecialchars() to prevent XSS.
🔹 7. Common File
Structure for PHP Projects
|
Folder/File |
Purpose |
|
index.php |
Entry point |
|
/includes/ |
Common code
like header/footer |
|
/assets/ |
CSS, JS,
images |
|
/config/ |
Database and
global settings |
|
/functions/ |
Reusable
logic |
|
.htaccess |
Apache
configuration (URL rewriting) |
🔹 8. Common Errors and
Troubleshooting
|
Error |
Cause
& Fix |
|
Parse error:
syntax error |
Check for
missing ;, {}, or quotes |
|
Undefined
variable |
Variable used
before assignment |
|
500 Internal
Server Error |
Misconfigured
server or permissions issue |
|
Blank page |
Enable error
reporting with: |
ini_set('display_errors',
1);
error_reporting(E_ALL);
✅ Recap Table: PHP Basics
|
Concept |
Example |
|
Output |
echo
"Hi"; |
|
Variable |
$name =
"Alice"; |
|
Comment |
// this is a comment |
|
Form input |
$_POST['fieldname'] |
|
HTML + PHP |
<?php echo
$var; ?> |
|
Server URL |
http://localhost/yourproject/ |
FAQs
1. What is PHP used for?
PHP is primarily used for creating dynamic web pages and server-side applications such as login systems, e-commerce platforms, and CMSs.
2. Is PHP still relevant in 2025?
✅ Absolutely. PHP continues to power most of the web and is essential in WordPress, Laravel, and web hosting environments.
3. Do I need to install anything to run PHP?
Yes — you can install XAMPP, MAMP, Laragon, or PHP CLI for local development.
4. What databases work with PHP?
MySQL
is the most commonly used with PHP, but it also supports PostgreSQL,
SQLite, and others.
5. What’s the difference between PHP and JavaScript?
PHP is a server-side scripting language, while JavaScript is primarily client-side, running in the browser.
6. Can I use PHP with HTML?
✅ Yes — PHP is often embedded inside HTML to create dynamic pages
7. What is a PHP file extension?
PHP
files have the .php extension and are executed on the server.
8. How do I send data from a form to PHP?
Use method="POST" or method="GET" in your form and access data in PHP using $_POST or $_GET.
9. Is PHP good for building APIs?
✅ Yes — PHP can be used to build RESTful APIs, especially with frameworks like Laravel or Slim.
10. What are some popular PHP frameworks?
Laravel, Symfony, CodeIgniter, Zend, and Slim are among the most used PHP frameworks.
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