What is PHP? An Easy Guide for Beginners

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If the internet were a car, you’d probably notice the shiny paintwork (the website design) and the comfy seats (the user experience). You’d admire the powerful engine of a flashy site like a high-performance sports car. But what you probably wouldn’t notice is the humble, reliable engine that powers most of the cars on the road. The one that starts every time, gets the job done without a fuss, and is trusted by mechanics everywhere.

That engine, for a huge chunk of the web, is PHP.

It might not have the trendy reputation of newer technologies, but PHP is the invisible workhorse that runs an astonishing portion of the internet. From your favourite blogger’s latest post to the world’s biggest social network, PHP is humming away in the background. In fact, if you’ve used Wikipedia, Facebook, or virtually any site built with WordPress (which is over 40% of all websites), you’ve used a PHP-powered service today.

So, what exactly is this powerhouse technology? Why do some developers love it while others are quick to criticise it? And in a world of ever-changing tech, how has it managed to stay so incredibly relevant?

Let’s pop the bonnet and take a look. This is the complete story of PHP, explained in plain English.

What is PHP, Really? Let’s Break It Down

At its heart, PHP is a server-side scripting language.

That sounds a bit jargony, so let’s use an analogy. Imagine you’re at a restaurant.

You, the user, look at a menu (the website).
You give your order to the waiter (your web browser, like Chrome or Safari).
The waiter takes your order back to the kitchen (the web server).

Now, this is where PHP comes in. The kitchen isn’t just a storeroom; it’s a dynamic place where things happen. The chef is PHP.

The chef takes your simple order and does a whole bunch of things with it. They might check the pantry for ingredients (a database), follow a recipe (code), and cook your meal exactly as you asked for it. They don’t just hand you a pre-packaged sandwich; they prepare a fresh meal just for you.

Once the meal is ready, the chef plates it up nicely and hands it back to the waiter. The waiter then brings you the finished dish—a fully prepared, ready-to-eat webpage.

That’s what “server-side” means. All the clever work happens on the server (the kitchen) before the result is ever sent to you. The code isn’t running on your computer; it’s running on a powerful computer somewhere else. Your browser just gets the final, simple output: HTML, which is the basic language of web pages.

The Three Key Ingredients of PHP

To understand what PHP does, it helps to know its three main roles:

It’s a Scripting Language: Unlike a compiled language where you write code and then have to build it into an executable file (like software you install), PHP is an “interpreted” language. The server reads the script line by line and executes the instructions on the fly, a bit like a live translator speaking as they listen. This makes it fast and flexible for web tasks.
It Creates Dynamic Content: A static website is like a printed flyer. The information is fixed. A PHP-powered website is like a digital noticeboard that updates in real-time. It can show you a personalised greeting, display the latest news headlines, or show you search results from a massive catalogue. The content is dynamic—it changes based on who you are, what time it is, or what you’ve asked for.
It Talks to Databases: This is PHP’s superpower. A database is like a giant, super-organised filing cabinet. PHP is the expert clerk who can instantly find, add, update, or remove information from that cabinet. When you log into a website, PHP takes the username and password you entered, checks them against the database, and decides whether to let you in. When you buy something online, PHP updates the stock levels in the shop’s database.

Without this ability to interact with databases, the web would be a very boring, static place.

A Quick Trip Through Time: The History of PHP

PHP wasn’t born in a sterile corporate lab. It started as a practical tool built by one person to solve his own problem.

The Early Days (1994): Personal Home Page Tools

In 1994, a Danish-Canadian programmer named Rasmus Lerdorf wanted to track who was looking at his online CV. He wrote a collection of simple tools in a language called C to help him out. He called it ‘Personal Home Page Tools’, or PHP Tools. It was never intended to be a full-blown programming language. It was just a set of shortcuts.

He shared his tools, and people loved them. They started using them for their own projects. As more people contributed, the project grew.

The Teenage Years (1997-2004): PHP Gets Serious

By 1997, the project had become much bigger. Two Israeli developers, Zeev Suraski and Andi Gutmans, found that the original PHP wasn’t powerful enough for an e-commerce application they were building. So, they rewrote the core engine from the ground up.

This new version was released as PHP 3, and it was a game-changer. It was faster, more stable, and had better features. They also renamed the project. PHP no longer stood for ‘Personal Home Page’; it now stood for PHP: Hypertext Preprocessor—a recursive acronym that only programmers could love.

The new core they built was called the Zend Engine, a combination of their first names, Zeev and Andi. This engine became the heart of PHP 4 (released in 2000), which cemented PHP’s popularity. It was easy to learn, web hosting was cheap, and a new generation of developers started building dynamic websites with it. This was the era of forums, guestbooks, and early content management systems (CMS).

Adulthood (2004-2015): Maturing with PHP 5

Released in 2004, PHP 5 was another huge leap. It introduced a much-improved system for ‘Object-Oriented Programming’ (OOP), which is a way of organising code that’s essential for building large, complex applications. This made PHP a serious contender for professional software development, not just a hobbyist’s tool.

During this time, the PHP ecosystem exploded. Powerful frameworks like Symfony and Zend Framework emerged, providing ready-made building blocks for developers. And, most importantly, a little project called WordPress was launched in 2003. Built on PHP, it made it possible for anyone to create a professional-looking blog or website without writing a single line of code.

The Renaissance (2015-Present): PHP 7 and 8

For a while, PHP’s reputation started to suffer. It was seen as slow and messy compared to newer, trendier languages. A planned PHP 6 got stuck in development hell and was eventually abandoned, which didn’t help.

Then came PHP 7 in 2015.

It was a complete revolution. The core Zend Engine was rewritten again, and the result was astonishing. PHP 7 was up to twice as fast as PHP 5. It used less memory and introduced modern features that brought it right up to date with its competitors.

PHP 8, released in 2020, continued this trend, adding even more performance improvements like the JIT (Just-In-Time) compiler and features that make writing clean, reliable code even easier. Modern PHP is a fast, mature, and powerful language that looks very different from its humble beginnings.

How Does PHP Actually Work? A Step-by-Step Guide

So, what happens when you click on a link to a PHP page? Let’s follow the journey from your click to the page appearing on your screen.

You Make a Request: You type www.example.co.uk/about.php into your browser and hit Enter.
The Browser Sends a Message: Your browser sends an HTTP request across the internet to the web server where example.co.uk is hosted.
The Server Finds the File: The web server (usually a piece of software like Apache or Nginx) locates the about.php file on its hard drive.
The Server Realises It’s a PHP File: The server sees the .php extension and knows it can’t just send the file back as it is. It contains instructions that need to be followed first.
PHP Gets to Work: The server passes the file to the PHP interpreter. This is the program that reads the PHP code.
The Code is Executed: The PHP interpreter runs the script from top to bottom. It might do things like:
- Fetch the latest blog posts from a database.
- Check if you’re logged in by looking at a cookie.
- Calculate the total price of your shopping basket.
- Put your name into a welcome message: <?php echo "Hello, Bob!"; ?>
The Output is Pure HTML: The end result of the PHP script is a plain block of text. This text is always simple HTML, the language all browsers understand. All the PHP code is gone, replaced by its output. The final result might look something like this: <p>Hello, Bob!</p>.
The Server Sends the HTML Back: The server takes this newly generated HTML and sends it back to your browser.
Your Browser Displays the Page: Your browser receives the HTML and renders it, showing you the final webpage. You, the user, never see the PHP code—only the finished product.

Think of it like ordering a bespoke suit. You don’t see the patterns, the cutting, or the stitching. You just get a perfectly tailored suit delivered to you. The PHP code is the tailoring process; the HTML is the final suit.

Why is PHP So Ridiculously Popular?

Despite what you might hear in some corners of the tech world, PHP’s popularity is undeniable. According to W3Techs, PHP is used by nearly 77% of all websites whose server-side programming language is known. That’s a staggering number. But why?

The WordPress Factor

This is the single biggest reason for PHP’s dominance. WordPress, the world’s most popular content management system, is built entirely on PHP. It powers everything from small personal blogs to massive news sites like The Sun and Metro, and even the official website of Number 10 Downing Street.

Because WordPress runs on PHP, the millions of businesses, creators, and organisations that use it are all, by extension, using PHP. This creates a massive, self-sustaining ecosystem.

It’s Easy to Get Started

PHP has a famously low barrier to entry. The syntax is forgiving and relatively easy to pick up compared to other languages. Crucially, it’s incredibly easy to deploy. Almost every web hosting package in the world, even the cheapest ones, comes with PHP pre-installed. You can write a script, upload it to a server, and it just works. You don’t need complex server configurations or specialised hosting, which is often the case for other languages like Python or Node.js.

A Massive and Mature Ecosystem

PHP has been around for over 25 years. That means there is a gigantic amount of documentation, tutorials, libraries, and forums available to help you solve any problem you might encounter. Whatever you’re trying to do, someone has probably done it before and written about it.

This maturity has also led to the development of world-class tools, including:

Package Managers: Composer is a brilliant tool that lets developers easily pull in pre-written libraries of code to use in their projects.
Frameworks: For building custom applications from scratch, modern PHP frameworks provide a solid foundation.
- Laravel: Known for its beautiful, elegant syntax and developer-friendly features, Laravel is currently the most popular PHP framework. It makes complex tasks like database management, authentication, and routing incredibly simple.
- Symfony: A set of reusable components and a framework for large-scale, enterprise-level applications. It’s known for its stability and is the foundation for many other projects, including the popular CMS, Drupal.

It’s Fast. No, Really.

This is one of the biggest misconceptions about PHP. While early versions were sluggish, modern PHP is a speed demon. The performance revolution in PHP 7 and the continued improvements in PHP 8 mean that for typical web requests, PHP is often faster than its main rivals, Python and Node.js. It’s been optimised over decades for one thing: building websites. And it does that job exceptionally well.

Addressing the Critics: Is PHP a “Bad” Language?

You don’t have to look far to find a developer with a strong, often negative, opinion about PHP. For years, it’s been the butt of jokes in the programming community. But is the criticism fair?

Most of it is rooted in history.

Inconsistent Design: In the early days, PHP grew organically rather than being designed. This led to some weird inconsistencies. For example, function names weren’t standardised. Some used underscores (str_split) while others didn’t (strpos). This made the language feel messy and hard to memorise. Modern tools and better documentation have largely solved this for developers, but the reputation lingers.
Security Woes: Because it was so easy to learn, many beginners wrote very insecure PHP code. It was easy to write code that was vulnerable to common attacks like SQL Injection or Cross-Site Scripting (XSS). This gave the language a reputation for being insecure. However, this was rarely the fault of the language itself, but rather the way it was used. Modern PHP, especially when used with a framework, is just as secure as any other language.
The “Messy Code” Problem: PHP makes it very easy to mix your logic (the PHP code) with your presentation (the HTML). In a single file, you could have database queries, business logic, and HTML all jumbled together. This can create a nightmare for maintaining or updating a project.

While this is possible, it’s not how modern PHP developers work. They use frameworks and template engines (like Twig or Blade) that enforce a clean separation, keeping the logic and the presentation in different files.

Essentially, most of the criticisms levelled at PHP are about things that were true 10 or 15 years ago. Modern PHP is a different beast entirely. It’s like criticising a modern Ford Focus for having the same performance as a Ford Escort from the 1990s.

Who is Using PHP Today?

The short answer is: almost everyone, whether they know it or not. Beyond the obvious WordPress sites, many household names rely on PHP.

Facebook: While they have a complex tech stack, Facebook was originally built in PHP. They invested so heavily in it that they created their own version called Hack and a virtual machine (HHVM) to run it at incredible scale.
Wikipedia: The world’s largest encyclopaedia, run by MediaWiki, is built on PHP. It handles billions of page views with remarkable efficiency.
Slack: The popular team communication tool uses PHP for its server-side backend.
Etsy: The global marketplace for handmade goods uses PHP to power its massive e-commerce platform.
UK Examples: Many UK government services, NHS digital platforms, and major e-commerce sites have PHP running at their core, often via systems like Drupal or Magento.

The Future of PHP: Brighter Than Ever

Far from fading away, PHP is actively evolving. The formation of the PHP Foundation in 2021 was a major step forward. It’s a non-profit organisation funded by major companies (like Automattic, the company behind WordPress) to ensure the language has a healthy, well-supported future.

The development team continues to release a new version every year, focused on:

Better Performance: Making the language even faster and more efficient.
Stronger Typing: Adding features that help developers catch bugs early and write more robust, reliable code.
Modern Syntax: Introducing new shortcuts and features that make the language cleaner and more enjoyable to write.

PHP has found its niche and completely dominates it. It’s the pragmatic, get-it-done language of the web. It may never be the “coolest” language on the block, but it doesn’t need to be. It’s the reliable, powerful, and ubiquitous engine that will continue to power a massive portion of the web for many years to come.

So next time you’re browsing a recipe blog, checking the news, or managing your own website, take a moment to appreciate the unseen engine working tirelessly in the background. Chances are, it’s PHP.

What is PHP? The Surprising Story of the Web’s Unseen Engine