PHP

PHP (which stands for the recursive initialism "PHP: Hypertext Preprocessor") is a general-purpose scripting language commonly used for web development. In fact, PHP is the most prevalent server-side programming language on the internet, with more than 75% of all websites utilising PHP to some degree (W³Techs.com). A large part of that impressive percentage is due to WordPress, which accounts for more than 40% of all websites on its own (W³Techs.com) and is itself coded in PHP.

In a typical setup for a website using PHP, when the server hosting the website receives a request (such as a web browser attempting to load a page on a website), the server processes and executes the PHP code, and then returns the result (which can be any type of data, but typically HTML in this context) as an HTTP response.

PHP is open-source, which means that the source code that makes up PHP is publicly available and may be redistributed and modified, and while it was originally released all the way back in 1995 it is still regularly updated to this day. With that said, the majority of websites that use PHP are not using the latest major version (PHP 8), with more than half of websites which use PHP utilising PHP 7, and a further 15% still using PHP 5 (interestingly, there actually is not a PHP 6! But that is a story for another time).

So, what does this all mean for you if you have a website using PHP, or you are considering creating one? Well, first, you are not alone! Like any programming language, PHP is not perfect, but it is certainly here to stay, at least for the foreseeable future. While there is an almost unending amount that could be said about PHP, for the purposes of this glossary, I'll leave you with some general considerations if you are, or may become, a member of that impressive statistic of website owners using PHP for their website.

• In general, the higher version of PHP that you are able to use, the better. Each new version of PHP addresses security vulnerabilities, fixes bugs, and improves on the performance of previous versions. However, depending on your situation, it may not be realistic to use the very latest version (remember, more than half of websites using PHP don't!). Still, it is always best to strive for the latest version that works for your particular situation.
• Following on from the previous point, if your website is using WordPress, you should technically be able to use PHP 8 (as long as your site's WordPress version is also up to date). However, if your website uses certain WordPress plugins or themes, you may run into issues trying to use anything newer than PHP 7. This is because, while WordPress itself has been updated to support PHP 8, many plugins and themes (which are typically created by myriad of other companies and developers, and all have varying levels of updates and support themselves) are not updated to support later versions of PHP. At the end of the day, the most important thing is that everything actually works, so if your site is using plugins or themes that don't support newer versions of PHP, it is okay to use a slightly older version instead.
• If you have a website that uses PHP but is not using WordPress, it is likely that your website is at least partially custom-built. In this case, updating your PHP version can be an even more daunting task because there is likely not a team of developers (as in the case of WordPress) who will be making periodic updates to the underlying code for you. While it probably isn't the end of the world to use an outdated version of PHP (depending on the purpose of your site, as any time that sensitive data is involved things should be handled with extra caution), it is still something you will want to be aware of. The most important reason to consider upgrading is security, and in general, the older the version of PHP, the more security vulnerabilities there are. If you know your specific version of PHP, you can check vulnerabilities for your version here.