When it comes to fundamental programming languages you should learn for web development, the answer is relatively clear: you can’t go wrong starting with the trio of HTML, CSS, and JavaScript. It can get a bit more murky though with some of the other languages you’ll hear mentioned in tech circles—specifically whether they’re helpful to learn as a web developer, and what exactly they’re used for. One programming language you’re sure to see referenced as you get familiar with tech is PHP. So what is it, and is it a useful programming language to learn for web development?

PHP Is a Scripting Language

PHP (an acronym for PHP: Hypertext Preprocessor) is a scripting language that’s generally used in “server-side” web development. (Don’t worry, I’ll explain exactly what this means below.) In order to sort it all out, it’s crucial to first understand what a scripting language is. Scripting languages (a family of programming languages including PHP as well as languages like JavaScript and Ruby) are a subset of coding languages used to automate processes that otherwise would need to be executed step-by-step in a site’s code every time they occur.

This includes things like dialogue boxes opening on a screen in response to a user’s actions, chatbots responding to defined user behavior with corresponding messages, or animation that happens when a user scrolls past a certain point on a page—any dynamic website functions that need to occur on screen without the user having to manually reload a site. Scripting languages like PHP are distinct from markup languages like HTML and CSS in the sense that while HTML and CSS determine the layout and look of web pages, scripting languages tell a static web page (built with HTML and CSS) to “do” specific actions. If you’ve spent any time reading about JavaScript, this might sound familiar. So is PHP just another way of accomplishing the things you can do with JavaScript? Not exactly.

PHP Is Used For Server-Side Scripting

As mentioned previously, PHP is typically used as a server-side language (as opposed to a language like JavaScript that’s generally executed on the client-side). So what does that mean? In programming terms, client-side refers to website activity that takes place locally on a user’s computer through the user’s web browser. Client-side languages like HTML, CSS, and JavaScript give instructions that web browsers can parse and translate into content on your computer screen. Notice JavaScript (a scripting language like PHP) is on that list. Again, the processes scripted by JavaScript take place on the client-side—JS provides instructions that can be understood by and executed in your web browser. Client-side is the side you see when you’re using the internet.

On the other hand, server-side activity involves a web browser sending requests to a web server (the software or hardware that stores a websites pages, images, media, and other assets), which then responds to the request with HTML code that can be processed and rendered by the web browser and turned into content on the user’s screen. The main difference here from client-side activity is the fact that this process involves communication with a server and isn’t completed entirely within the client’s browser. In other words, a client-side scripting language like JavaScript can automate tasks involving content that’s already available to a user in their web browser, but a server-side scripting language like PHP is used to request content from a website’s server or database and make that content visible and accessible for the site’s user. In order to maintain website efficiency, loading speeds, and storage capacity, not all assets can be stored locally on web pages at all times.

For example, a PHP script can make your three most recent blog posts appear automatically on your site’s front page. In this instance, the posts themselves are stored on the site’s server and called up when they occupy one of the three most recently published slots. This avoids both preloading the posts on your site and necessitating a site admin to load and update the posts when new stories are published. PHP scripts can also involve conditional (if/else/endif) statements that direct your site to change its display and add content from your web server as needed. This can include actions such as dictating that if the site administrator uploads a video link to “x” field, then the site will load the video from its server and display it for the user. The script can further state that if the admin does not upload a link, then the page will show “y” default image instead. PHP’s server-side actions introduce a whole new level of dynamic possibilities to a website (above and beyond the static features offered by HTML and CSS, and even the dynamic client-side content made possible by JavaScript).

PHP and WordPress

PHP’s functionality plays a particularly large role when it comes to WordPress development. While it’s possible to build functional WordPress sites without knowing PHP, PHP is the engine behind custom WordPress themes and plugins. When creating these kinds of custom WordPress features, PHP is the scripting language used to communicate with the WordPress site’s server and deliver requested content and actions to the user’s screen. If you build a WordPress site using template themes and plugins you’ll still be passively implementing PHP, but in order to create your own themes, plugins, or alter WordPress’ default behavior, you’ll need to develop hands-on PHP skills. WordPress—a content management system that allows you to create and publish digital content online—is a particularly attractive platform for web development since its learning curve make room for complete beginners (who can rely on menu options and default templates), but it keeps the door open for advanced users who can take advantage of PHP and create a more custom experience for clients. Learning your way around WordPress basics alone will already put you in position to do paid WordPress developer work, but learning PHP will make you that much more qualified to carve out a niche as a serious WordPress developer.

The takeaway here is that—while PHP isn’t ahead of HTML, CSS, and JavaScript on the list of must-learn web developer skills—it’s a skill that anyone looking to round out a developer toolkit should definitely consider adding to their arsenal. It’s certainly possible to build static websites with only HTML and CSS (and to build websites with dynamic content using JavaScript), but introducing a server-side language into the mix will drastically increase the kinds of websites you can tackle and clients you can land. PHP in particular will also give you access to the lucrative world of WordPress customization. And so—when it comes to the alphabet soup of coding languages—PHP are three letters you should definitely keep in mind.