PHP Introduction

What is PHP?

PHP (PHP: Hypertext Preprocessor) is a scripting language designed for the web. Unlike JavaScript which runs in the browser, PHP runs on the web server. When someone requests a web page, the server executes the PHP code and sends the resulting HTML back to the visitor's browser.

• PHP is interpreted — no separate compile step.
• PHP code is embedded inside HTML files, not separate from them.
• Created by Rasmus Lerdorf in 1994; PHP 8 is the current major version.

Server-side scripting

Because PHP runs on the server, the visitor never sees your source code — only the output it produces. That makes PHP a natural fit for anything involving databases, sessions, cookies, and user authentication.

<!-- This is what YOU write -->
<p>Hello, <?php echo "PHP Academy"; ?>!</p>

<!-- This is what the BROWSER receives -->
<p>Hello, PHP Academy!</p>

Hello, PHP Academy!

• The browser only ever receives the generated output.
• You can mix plain HTML and PHP in the same file.

Where PHP runs

To run PHP locally you need the PHP interpreter and, typically, a web server. Common local setups are XAMPP, Laragon, or WAMP on Windows. The interpreter processes any file whose code sits between the opening tag <?php and the closing tag ?>.

Your first PHP file

Save the following as index.php. The opening tag tells the interpreter to start executing; text outside the tags is passed through untouched.

<?php
echo "Hello, PHP Academy!";
?>

Hello, PHP Academy!

• echo sends text to the output.
• The trailing ?> is optional at the end of a file and is often omitted.
• Every statement ends with a semicolon.

Comments

Comments are ignored by the interpreter. Use them to explain what your code does.

<?php
// Single-line comment
# Another single-line comment

/*
 * Multi-line comment.
 * Useful for longer notes.
 */

echo "Learning PHP"; // Comments can trail code too
?>

Learning PHP