PHP Zero to Advanced #1: Introduction & Setup

PHP powers a huge share of the web, from small personal blogs to large platforms such as WordPress, Wikipedia, and countless e-commerce sites. It is easy to start with, runs almost everywhere, and modern PHP (version 8 and later) is fast, typed, and pleasant to write. In this series we will go from zero to building a small REST API with authentication, tests, and secure database access.

In this first part you will learn what PHP is, install it, check your version, run PHP from the command line, start the built-in development server, and write your first scripts.

What Is PHP?

PHP (a recursive acronym for PHP: Hypertext Preprocessor) is a server-side scripting language. When a browser requests a .php page, the web server runs the PHP code and sends back the result, usually HTML or JSON. The browser never sees your PHP source code.

• Server-side: code runs on the server, not in the browser (unlike JavaScript in the browser).
• Interpreted: you do not compile anything manually; save the file and run it.
• Versatile: PHP can render web pages, build APIs, run CLI scripts, and process background jobs.
• Modern: PHP 8.x brings union types, enums, readonly properties, the match expression, attributes, and a JIT compiler.

Throughout this series we target PHP 8.2 or newer.

Installing PHP

Pick the method that matches your operating system:

# macOS (Homebrew)
brew install php

# Ubuntu / Debian
sudo apt update
sudo apt install php-cli php-mbstring php-xml php-sqlite3

# Windows: download from windows.php.net or use Laragon / XAMPP

If you prefer an all-in-one bundle that includes a web server and database, tools like Laravel Herd, Laragon, or XAMPP work fine too. For this series, the PHP command-line interface (CLI) is all you need.

Once installed, verify the version:

php -v

Output:

PHP 8.3.12 (cli) (built: Sep 24 2024 18:08:04) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.3.12, Copyright (c) Zend Technologies
    with Zend OPcache v8.3.12, Copyright (c), by Zend Technologies

Your exact version and build date will differ. What matters is that the major version is 8 and the minor version is 2 or higher.

Your First Script

Create a file called hello.php. Every PHP file starts with the opening tag <?php. In files that contain only PHP, you should omit the closing tag ?> to avoid accidental whitespace being sent to the output.

<?php

echo "Hello, World!";

Output:

Hello, World!

Run it from your terminal with the PHP CLI:

php hello.php

Output:

Hello, World!

Congratulations, you just ran your first PHP program. Note the semicolon at the end of the statement: every PHP statement must end with ;.

The Built-in Development Server

PHP ships with a small web server for local development. You do not need Apache or Nginx to start learning. Inside a folder that contains your PHP files, run:

mkdir my-first-php && cd my-first-php
php -S localhost:8000

Output:

[Tue Oct 13 09:00:00 2026] PHP 8.3.12 Development Server (http://localhost:8000) started

Now create index.php in the same folder. PHP can be mixed with HTML: anything outside <?php ... ?> is sent to the browser as-is.

<!DOCTYPE html>
<html>
<head>
    <title>My First PHP Page</title>
</head>
<body>
    <h1>Welcome!</h1>
    <p>Today is <?php echo date('Y-m-d'); ?></p>
    <p>PHP version: <?= PHP_VERSION ?></p>
</body>
</html>

Open http://localhost:8000 in your browser and you will see the heading, today's date, and your PHP version. The short tag <?= ... ?> is a shortcut for <?php echo ... ?>. Stop the server with Ctrl+C.

The built-in server is for development only. In production, use a proper web server such as Nginx or Apache with PHP-FPM.

echo, print, and Comments

echo is the most common way to send output. print works similarly but accepts only one argument. Note the difference between double quotes and single quotes:

<?php

echo "Hello from echo\n";
print "Hello from print\n";
echo "One", " ", "Two", "\n";   // echo accepts multiple arguments

$name = "Budi";
echo "Hi, $name!\n";            // variables inside double quotes are interpolated
echo 'Hi, $name!' . "\n";       // single quotes are literal

Output:

Hello from echo
Hello from print
One Two
Hi, Budi!
Hi, $name!

The . operator concatenates (joins) strings, and "\n" is a newline character, which only works inside double quotes. We will cover strings in depth in the next part.

Comments help explain your code and are ignored when the script runs:

<?php

// A single-line comment
# Also a single-line comment

/*
 * A multi-line comment.
 * Useful for longer explanations.
 */

echo "Comments are ignored by PHP";

Output:

Comments are ignored by PHP

You can also inspect your environment with a few built-in constants and functions:

<?php

echo "PHP version: " . PHP_VERSION . "\n";
echo "Major version: " . PHP_MAJOR_VERSION . "\n";
echo "Max int: " . PHP_INT_MAX . "\n";
echo "Running from: " . php_sapi_name() . "\n";

Output:

PHP version: 8.3.12
Major version: 8
Max int: 9223372036854775807
Running from: cli

Common Mistakes

• Forgetting the semicolon. This is the classic beginner error:

<?php

echo "First line"
echo "Second line";

Output:

Parse error: syntax error, unexpected token "echo", expecting "," or ";" in /path/to/script.php on line 4

• Opening the file directly in the browser (file:///.../index.php). The browser will show raw code or download it. PHP must be executed by a server, so use php -S.
• Using single quotes when you want interpolation. 'Hi, $name' prints the literal text $name.
• Adding a closing ?> in pure PHP files. Trailing spaces after it can cause "headers already sent" errors later.
• Running an old PHP version. Many examples in this series use PHP 8.2+ features. Always check php -v.

Exercise

Create a file about.php that stores your name, city, and the year you started learning PHP in variables, then prints three sentences. Here is one possible solution:

<?php

$name = "Siti";
$city = "Bandung";
$year = 2026;

echo "My name is $name.\n";
echo "I live in $city.\n";
echo "I started learning PHP in $year.\n";

Output:

My name is Siti.
I live in Bandung.
I started learning PHP in 2026.

As a bonus, serve it with php -S localhost:8000 and open http://localhost:8000/about.php. Notice that the browser joins the lines together, because \n is not an HTML line break. Try replacing it with <br>.

Summary

• PHP is a server-side language that generates HTML, JSON, or any text output.
• Check your installation with php -v and run scripts with php file.php.
• Use php -S localhost:8000 for a quick local development server.
• PHP files start with <?php, statements end with ;, and echo prints output.
• Double quotes interpolate variables, single quotes do not.

In Part 2 we will dive into variables, data types, operators, and working with strings.