What is PHP? A Thorough Explanation for Absolute Beginners

If you find yourself diving deeper into the topic of WordPress, content management systems, and websites, a term you will quickly stumble upon is “PHP.” You will likely hear how crucial PHP is for the Internet and that it is what’s powering WordPress websites.

However, what exactly is PHP, and why is it so important?

The short answer is that it’s a general-purpose, server-side scripting language. That said, unless you are already knowledgeable in programming and web development, that probably doesn’t make things much clearer. 

In order to help you better understand this topic, we’ll cover PHP in detail below. You’ll learn what PHP is, why it matters, and how it relates to WordPress and pretty much everything you do online. We promise you’ll be surprised to hear how much you likely rely on PHP every day.

1. What is PHP? History, features, and benefits
   1. PHP features
   2. Benefits of PHP
2. How PHP works: Creating dynamic web content
3. PHP and WordPress: The CMS’ heart and soul
   1. Powering themes and plugins
   2. Without PHP, there would be no WordPress
4. PHP in everyday life: You rely on it more often than you think
   1. Other abilities of PHP
5. What is PHP? It is the web’s backbone

The original developer of PHP was a Danish-Canadian programmer named Rasmus Lerdorf. He first created the language in the mid 1990s to build tools for his own website; that’s why PHP originally stood for “Personal Home Page.” Today, it stands for the recursive acronym “Hypertext Preprocessor” and development and support has been taken over by the PHP Group.

PHP has some notable features, many of which are applicable to the way WordPress works:

Open Source: The first thing that is important to note is that, like WordPress, PHP is open source. That means it does not belong to any one business entity. It also means that it’s free to download and use for any purpose.

Also like WordPress, PHP is maintained by a number of volunteers around the world. The next major release, 8.4, will be available November 21, 2024.

Finally, both WordPress and PHP are community-funded––while WordPress has the WordPress Foundation, The PHP Foundation’s mission is to “ensure the long-term prosperity of the PHP language.” Automattic is a proud Platinum Sponsor of The PHP Foundation.

Server Side: PHP is a server-side language, which means it executes on the server and not in the user’s browser.

For example, PHP’s most frequent application is for creating HTML documents for websites. Even though there are PHP files on the server, the browser does not receive the PHP code; instead, it receives the finished HTML documents for display. This is different from client-side languages like JavaScript where the processing happens directly in the user’s browser after downloading the JavaScript files.

To make things clearer, server-side languages are a bit like going to a restaurant. You send an order to the kitchen, they prepare the meal, and it arrives at your table ready to eat. Client-side languages, on the other hand, are like meal-delivery services. While they provide you with all the necessary ingredients, you still have to put them together in your own kitchen.

General Purpose: PHP is also a general-purpose programming language. You can use it for command-line scripting, creating desktop applications, and more. However, its primary application is in web development. 

Ubiquitous: According to W3Techs, the language is present on 75.7% of all websites. That includes some famous ones, as you will see below.

In addition, it forms the backbone of many content management systems like Drupal, Joomla!, and—the most popular of them all—WordPress.

PHP is one of the biggest open source success stories, as much of the modern Internet depends on it to work.

You might be asking yourself why the usage of PHP is so widespread. There are many good reasons for that, but here are just a few:

• Beginner-Friendly: PHP is relatively easy for beginners to learn due to its intuitive syntax. There are also plenty of tools and frameworks available to make coding easier.
• Wide Community: The language has a vast and active community of developers worldwide. This means there are loads of online resources, forums, and other places where users can seek help and find ready-made solutions to common problems.
• Cross-Platform Compatibility: PHP is compatible with popular operating systems, including Windows, MacOS, Linux, and Unix. It also works on various web servers such as Apache, NGINX, and Microsoft IIS.
• Database Connectivity: In addition, it works with a number of different database formats, such as MySQL, MongoDB, PostgreSQL, SQLite, Oracle, and more. PHP can execute SQL queries, retrieve, update and delete data, and handle database connections and transactions.
• Cost-Effective: As we have already learned, the programming language is free to use, distribute, and modify. That eliminates the need for expensive licensing fees and reduces development costs, making it an economical choice for web development projects.
• Scalability: PHP is capable of handling high traffic loads and can easily scale. You can use it together with caching techniques and other optimization strategies to enhance performance. Plus, it’s generally faster than some other programming languages, such as Python.

One of the main reasons why PHP is so popular for web development is that it seamlessly integrates with various technologies and services commonly used in this area. Examples include HTTP, POP3, IMAP, and more. 

One of its main advantages is that it is highly compatible with HTML, the main language used to create and display websites. In fact, it’s possible to use PHP code in HTML files and vice versa.

<div class="about__section is-feature has-subtle-background-color">
	<div class="column">
		<h2><?php _e( 'Shape the future of the web with WordPress' ); ?></h2>
		<p><?php _e( 'Finding the area that aligns with your skills and interests is the first step toward meaningful contribution. With more than 20 Make WordPress teams working on different parts of the open source WordPress project, there’s a place for everyone, no matter what your skill set is.' ); ?></p>
		<p><a href="<?php echo esc_url( __( 'https://make.wordpress.org/contribute/' ) ); ?>"><?php _e( 'Find your team &rarr;' ); ?></a></p>
	</div>
</div>

Above you can see how both languages appear in the same file. The PHP markup is delineated by opening and closing brackets (<?php and ?>) so that the server knows where it ends and begins. However, the PHP code itself is inside an HTML <p> element. The _e function is a WordPress function used for localization, which allows for easy translations across the WordPress software.

The main benefit of this is that using PHP allows web developers to display dynamic content in otherwise static web pages. For example, PHP is able to pull content directly from databases, making it great for templating. You can create a fixed layout for all web pages but then display different content depending on the page a user is on.

This is vastly different from pure HTML, where the content needs to be hard-coded in the page file in order for the browser to show it. PHP, on the other hand, can add it on the fly as needed. That’s one of the main benefits of this programming language—the ability to dynamically combine and display content from different sources and of different kinds according to what the user requests.

As a WordPress user, PHP is especially important. The programming language forms the basis of much of what WordPress can do. It’s what allows you to create, edit, and delete pages, posts, media, and other content. That’s why you see that a lot of files that end in .php when you look in the directory of any WordPress installation.

It’s also why, when installing WordPress on a server, the system requirements insist that PHP be present. In recent years JavaScript has been playing a bigger and bigger role in the WordPress ecosystem, mainly because of the adoption of the Gutenberg editor. That said, PHP is still the main workhorse in the background.

What are some of WordPress’ main tasks powered by PHP? Before the advent of block themes, WordPress themes were all written mostly in PHP, especially page template files. In fact, if you look at the template hierarchy, you can see that WordPress has PHP files for pretty much all pages and theme components.

Why? So we have the ability to create a single layout for one type of content and then dynamically display what’s saved in the database for a particular piece of content.

That way, if you have 300 pages of the same kind on your site, you don’t need a file for each as you would on a pure HTML website. Instead, you just need one single page template file; PHP can then populate each individual page with its specific content.

PHP also makes it easy to compartmentalize different parts of your theme. For example, it’s very common to not have the markup for a footer in each file. Instead you can create a separate footer.php file and call it into your templates where needed. That way, if you want to modify the footer layout, you only have to make changes in a singular place—the footer.php file.

The same is true for plugins, aka collections of PHP files that contain the necessary markup for adding extra functionality to your WordPress site. When you activate a plugin, it gets added to the rest of your website code and can provide the functionality you are looking for.

All of the above is only made possible by the flexibility that PHP offers. Besides the benefits we have discussed before, this is the main reason why WordPress relies on PHP to the extent that it does; PHP offers a ton of flexible functionality specifically for web development. PHP’s capabilities in content management, working with databases, and its modularity all make it a perfect candidate for powering the most popular website builder there is.

This also means that if you know PHP, it opens up a lot more possibilities to modify your WordPress website. You can write custom plugins, make changes to (non-block) themes and page templates, introduce functionality to functions.php, and so much more. So, if you want to improve your WordPress skill set, learning PHP is not a bad place to start.

Besides WordPress, you might actually be unaware how much of your general everyday online interactions are enabled by PHP. There are a number of very well-known websites that use PHP to run and many common processes that the programming language performs online:

• Facebook: The largest social network in existence was initially built using PHP. While they have moved away from the programming language over time, it still plays a significant role in their infrastructure.
• Wikipedia: The world’s biggest online encyclopedia also relies heavily on PHP for its back end operations, content management, and user interactions.
• Tumblr: This microblogging and social networking platform employs PHP to power its vast network of user-generated content and social interactions. We’re actually in the process of migrating Tumblr’s backend to run on WordPress; if you’re interested in being a part of this exciting project, leave your information here.
• Slack: This widely-used team collaboration and communication platform utilizes PHP for its back-end operations, real-time messaging, and API integrations.

And this is just the tip of the iceberg. There are countless other examples of well-known web staples that exist in part because of PHP.

Up until this point, we’ve mostly talked about PHP in the context of creating and outputting HTML markup; however, the programming language is involved in a lot more that you probably take advantage of on a daily basis:

• Form Processing: PHP can process and validate data submitted by users via forms. It’s also capable of performing actions such as storing data in a database, sending email notifications, or generating dynamic responses based on user input. Plus, it comes with encryption to keep the submitted data safe.
• User Authentication: It can also handle user authentication by verifying login credentials. PHP allows you to implement user registration and login/logout functionality, and it can control access to different areas of your website or application. For example: user roles.
• Session Management: PHP can also manage user sessions, store session data, and track user activity. Among other things, this allows you to save user preferences. PHP can also set cookies and receive cookie data.
• File Manipulation: The programming language provides a wide range of functions for file manipulation, such as reading and writing files, uploading files from forms, creating directories, and modifying file permissions. This comes in handy for managing files on the server through other applications (like WordPress).
• Email Handling: PHP comes with functions to send emails from a server. This allows you to build features like contact forms, email notifications, and automated email responses.
• Third-Party Communication: With PHP you can interact with external APIs and web services. It makes it possible to integrate with other applications, retrieve data from remote servers, and perform actions like posting to social media platforms.

If you’re an everyday WordPress user or non-developer, you probably don’t spend a lot of time thinking about how much of your online experience is possible thanks to the humble PHP. However, the more you dive into this topic, the more you’ll realize how much you rely on it.

Who knew an open source solution was at the heart of what makes the World Wide Web tick? From the largest content management system in the world to well-known web entities, so much of what we take for granted exists because of it.

There are good reasons why it’s so widespread; from its powerful capabilities over its wide support system to ongoing development and support, there is a lot that speaks for PHP as the go-to solution for web projects.

Since it’s also beginner friendly, learning some PHP skills is definitely a good place to start if you want to dive deeper into the technical aspects of WordPress and web development.