What is PHP & How Does it Work?

PHP has been a key player in web development for decades, and it still powers a huge portion of the internet today. Whether you're building a site from scratch or managing one that's already live, having a handle on what PHP is—and what it can do—can make a real difference.

Let's break it down in a way that's easy to follow, without getting too far into the weeds.

What Is PHP?

PHP stands for PHP: Hypertext Preprocessor. Yes, it's a bit of a recursive acronym. What matters more is that it's a server-side scripting language—which means it runs on the web server, not in your browser. When someone visits a webpage that uses PHP, the server processes the PHP code first and sends the result (usually HTML) to the browser.

Think of it this way: HTML handles how things look, PHP handles what they do. If a website needs to display different information depending on who's visiting, or if it has interactive features like forms or user logins, PHP is often what's making that happen behind the scenes.

Why PHP Took Off (And Still Has a Place)

PHP caught on quickly in the early days of the web, and for good reason:

• It's relatively easy to learn. You can write your first script in a few lines, and you don't need to install anything special to get started on most web servers.
  
• It's purpose-built for the web. While some languages are adapted for web use, PHP was built with websites in mind.
  
• There's tons of support out there. Whether it's tutorials, libraries, or whole platforms like WordPress, PHP has been around long enough to build a strong foundation of resources.

Even now, with other languages and frameworks in the mix, PHP remains a solid choice—especially for projects where getting something up and running quickly matters.

If you're deciding between web server options for PHP hosting, it's helpful to review a comparison like Apache vs NGINX to understand performance tradeoffs and compatibility.

How PHP Works Behind the Scenes

Let's say you visit a webpage that ends in .php. When your browser sends that request, the web server checks the file type and sees that it contains PHP code. Instead of sending the raw file back, the server processes the PHP first. Whatever that script generates—usually HTML—is what gets sent to your browser.

You never actually see the PHP code itself. You just see the result of what it produced. This is one of PHP's key strengths: it can quietly handle all the logic and database work in the background, while keeping things clean and user-friendly on the front end.

Here's a simple example:

<?php
echo "Hello, visitor!";
?>

When the server runs this script, it returns:

Hello, visitor!

That's all the browser shows. If you looked at the page source in your browser, you wouldn't see any PHP—just the plain text output. This makes it harder for someone to peek at how your site works under the hood, and it also keeps sensitive logic (like user authentication or database queries) hidden from the public.

It's worth pointing out that PHP can do a lot more than print messages. It can generate entire web pages on the fly based on data pulled from a database, user input, session details, or even the time of day. The ability to dynamically build and serve content like this—without exposing the logic behind it—is one reason PHP is still widely used today.

If you're running a website on a cPanel or WHM-based hosting environment, the way PHP behaves can also depend on how it's configured at the server level. Things like memory limits, execution time, and PHP handlers all influence performance and compatibility. (For a closer look, you can check out our guide on Choosing the Right PHP Handler in WHM.)

PHP and Databases: A Strong Match

One of PHP's best features is how well it works with databases. Most dynamic websites pull content from a database—like user profiles, blog posts, or product info—and PHP is often the tool used to grab that data and show it on the page.

MySQL is the most common pairing, though PHP also works well with MariaDB, PostgreSQL, SQLite, and others. The two go hand-in-hand: PHP sends a query, the database responds with results, and PHP then turns those results into something users can interact with.

Example use cases include:

• Showing product details based on a user's search
  
• Displaying recent blog posts or comments
  
• Managing user accounts and passwords

If you're hosting multiple sites or users on the same server, data isolation in shared hosting becomes important when PHP applications access sensitive database content.

Common Things People Use PHP For

PHP is flexible enough to support a wide range of functionality, which is why it's still a go-to for many developers and site owners. Here are some of the most common ways PHP is used today:

Dynamic Content

PHP makes it easy to serve different content based on the user, time of day, location, or any number of other factors. For example, an online store might display products related to a user's browsing history or adjust pricing based on a promotion. News sites often use PHP to pull in and format the latest articles automatically. Instead of relying on static HTML pages, PHP helps sites stay current and personalized.

Forms

Whether it's a simple contact form or a multi-step survey, PHP is often what processes that input behind the scenes. It can validate fields, sanitize entries, send confirmation emails, and store submissions in a database. Form handling is one of the first things people build when learning PHP, and it remains a core use case for real-world sites.

Authentication

User login systems are a natural fit for PHP. It can manage sessions, check passwords, handle signups, and enforce permissions. Whether you're building a member-only site or just need admin access for editing content, PHP gives you the tools to handle it securely. Adding features like two-factor authentication or password resets is also possible with relatively little overhead.

Content Management Systems (CMS)

PHP powers many of the most widely used CMS platforms, like WordPress, Joomla, and Drupal. These systems let users publish and manage content without writing code, but it's PHP that makes them function. From loading templates to managing plugins and themes, PHP handles the logic that brings a CMS to life.

File Handling

PHP can read, write, and manipulate files on the server. This makes it a good choice for systems that allow file uploads—such as user-submitted images or documents. It can also generate new files (like PDFs or CSVs), resize images, or convert file types. Whether you're managing digital assets or generating custom reports, PHP has built-in tools to work with files efficiently.

Email Automation

Automated emails—like confirmation messages, password reset links, or order updates—are often handled by PHP scripts. It can integrate with SMTP services, build dynamic message content, and log activity for tracking purposes. For small websites, sending email directly from the server is common. For larger applications, PHP can easily connect with transactional email services to offload the work.

Keeping PHP Up to Date

Like any programming language, PHP evolves. Each new version brings better performance, modern features, and security fixes. Running outdated PHP not only slows things down—it also increases risk.

Recent versions (PHP 8 and up) added features that help developers write cleaner, more reliable code, like:

• Stronger type enforcement
  
• Better error reporting
  
• Performance improvements across the board
  

Keeping PHP and related software current also helps defend against common server exploits that can put your site at risk.

If you're building with PHP, or even just hosting a PHP-based site, it's worth making sure the version in use is current.

A Few Things to Keep in Mind

Because PHP has been around for a long time, there's a mix of old and modern code out there. Some older practices aren't considered safe or effective anymore, so it's worth staying abreast with current tutorials, official documentation, and actively maintained libraries.

PHP gives you all the building blocks you need to build secure and reliable applications—but they need to be used the right way. Here are a few basics to keep in mind, especially when your site interacts with users or stores data:

Sanitize and validate all user input

Any time someone fills out a form, uploads a file, or submits data in any way, there's a risk that something unwanted—or even harmful—could be sent to your server.

• Sanitizing means cleaning up the data so it's safe to process or display.
  
• Validating means checking that the data fits the rules you expect (for example, making sure an email field actually looks like an email address).

This protects your application from common issues like broken layouts, missing data, or more serious security problems like script injections.

Use prepared statements when working with databases

SQL injection is one of the oldest and most common security threats, but it's also easy to avoid if you're using the right tools. Prepared statements help separate the actual SQL query from the data being inserted, so even if someone tries to sneak malicious content into a form, it won't execute as part of the query.

PHP supports this out of the box with PDO and MySQLi.

$stmt = $pdo->prepare('SELECT * FROM users WHERE email = :email');
$stmt->execute(['email' => $inputEmail]);

This approach is cleaner, safer, and easier to manage than writing raw SQL strings with variables inserted directly.

Keep software and frameworks updated

Whether it's PHP itself, a third-party library, or a content management system like WordPress, updates often include security fixes and improvements. Regular maintenance helps keep PHP websites secure on shared hosting and reduces exposure to known issues.

Be sure to update not just your PHP version but also any packages, plugins, or tools you're using.

Use a framework for larger projects

If your project starts to grow beyond a few scripts, a PHP framework can help keep things organized. Tools like Laravel and Symfony are popular because they:

• Adhere to standard coding practices
  
• Handle routing, database access, and templating
  
• Include built-in tools to help with authentication, validation, etc.
  

This can save time and reduce errors—especially if you're working on a team or planning to maintain the project long-term.

Frameworks can also improve performance, which matters when you consider how web hosting affects SEO and site speed.

Wrapping Up

PHP has been around for a long time, but it's not just holding on out of habit. It's still widely used for a reason: it's accessible, capable, and fits naturally into the flow of building for the web.

Whether you're learning how websites work or you're already working on a custom-built project, understanding PHP gives you the ability to do more, tweak things that don't quite fit, or build something entirely from scratch.

If you're working in a web hosting environment or managing your own server, chances are PHP is already there. Knowing how to use it—or at least what it's doing—can save you time, help you troubleshoot issues, and open up new ways to improve your site.