PHP Web Development – Build Dynamic, Interactive, and Secure Web Applications

Learn the essential components of PHP Web Development including form handling, GET/POST requests, sessions, file uploads, email sending, and input sanitization.

Introduction – Why Learn PHP Web Development?

PHP powers over 70% of dynamic websites on the internet today. From handling forms and sessions to uploading files and sending emails—PHP is a robust server-side scripting language tailored for web development. Learning PHP for web development helps you build secure, scalable, and data-driven applications.

In this guide, you’ll explore:

• PHP’s key role in form handling, session control, and data sanitization
• How to handle GET/POST requests securely
• How to create interactive features like file uploads and flash messages

Topics Covered

PHP Web Concepts

PHP runs on the server and outputs HTML to the browser. It processes form data, handles file uploads, and manages session state between pages.

PHP GET & POST

GET appends form data to the URL; POST sends it invisibly in the HTTP body.

// POST example
$name = $_POST['username'];
echo "Hello, $name!";

PHP Form Handling

Use $_GET or $_POST to collect form input and process logic.

<form method="post">
  <input type="text" name="name">
  <input type="submit">
</form>

<?php echo $_POST['name']; ?>

PHP Form Validation

Ensure that fields are not empty or malformed.

if (empty($_POST['email'])) {
  echo "Email is required";
}

PHP Form Email/URL

Validate email and URL formats with built-in filters.

$email = $_POST['email'];
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
  echo "Invalid Email";
}

PHP Complete Form

Combine fields, validation, sanitization, and confirmation in a full working form.

if ($_SERVER["REQUEST_METHOD"] == "POST") {
  $name = htmlspecialchars(trim($_POST["name"]));
  echo "Welcome $name";
}

PHP File Uploading

Enable users to upload files securely using move_uploaded_file.

if (move_uploaded_file($_FILES["file"]["tmp_name"], "uploads/" . $_FILES["file"]["name"])) {
  echo "File uploaded!";
}

PHP Sending Emails

Use mail() or libraries like PHPMailer to send emails.

mail("to@example.com", "Subject", "Message body");

PHP Sanitize Input

Sanitize inputs to protect against cross-site scripting (XSS) and injection.

$name = htmlspecialchars($_POST['name']);

PHP Post—Redirect—Get (PRG)

PRG prevents form resubmissions using header("Location: success.php") after POST.

if ($_SERVER["REQUEST_METHOD"] == "POST") {
  // Process...
  header("Location: thankyou.php");
}

PHP Flash Messages

Show one-time notifications using sessions.

$_SESSION['message'] = "Data saved!";
echo $_SESSION['message'];
unset($_SESSION['message']);

PHP Session Options

Configure session lifetime, save path, and cookie settings.

ini_set('session.gc_maxlifetime', 1800);
session_set_cookie_params(1800);
session_start();

PHP Cookies

Set and retrieve cookies to remember data on the client.

setcookie("user", "John", time() + 3600);
echo $_COOKIE["user"];

PHP Sessions

Maintain login or form data across pages with $_SESSION.

session_start();
$_SESSION["username"] = "Admin";
echo $_SESSION["username"];

Summary – Recap & Next Steps

PHP web development provides powerful tools for managing user data, handling forms, uploading files, and maintaining session state. From validating inputs to displaying dynamic content, PHP bridges client interaction and server logic seamlessly.

Key Takeaways:

• Use POST for sensitive form submissions, and always validate inputs
• Store persistent user data with sessions and cookies
• Improve UX with flash messages and PRG pattern

Real-World Relevance:
PHP is the engine behind WordPress, Laravel, Joomla, and many eCommerce and CMS platforms.

Next Up: Explore PHP Security Best Practices to protect your web apps.

FAQ – PHP Web Development

What’s the difference between GET and POST in PHP?
GET appends data to the URL; POST keeps data in the request body for better security.

How do I validate form inputs in PHP?
Use empty() to check for blank fields and filter_var() for format validation like emails or URLs.

Can I upload files using PHP?
Yes, use $_FILES along with move_uploaded_file() to process uploaded files.

What are sessions and how are they used?
Sessions store user data across pages using $_SESSION and are ideal for login or cart systems.

How do I prevent form resubmission?
Use the Post-Redirect-Get (PRG) pattern with a header() call after form processing.