PHP

PHP is a programming language for the web. It doesn’t run in the user’s browser, but on the server — that is, the computer that delivers a web page. When someone requests a page, the server executes the PHP code, assembles it into a finished HTML page, and sends it to the browser. The user sees the result, never the source code. PHP stands for “PHP: Hypertext Preprocessor” — a self-referential acronym chosen with a wink, typical of programmer culture. The language first appeared in 1994 and is now among the most widely used server-side languages in the world.

PHP’s weight on the web

Estimates suggest that around 75 percent of all websites with known server technology run on PHP. This is mainly due to WordPress, the most widespread system for building websites, which is written entirely in PHP. Wikipedia, Facebook in its early years, and many other major platforms also relied on PHP.

This prevalence is no coincidence. From the start, PHP was easy to learn and could be embedded directly into HTML without setting up an elaborate project structure. Web hosting providers supported PHP early and widely. This made it very easy for developers around the world to get started — and it’s still what keeps PHP ubiquitous on the web today.

How PHP builds a page

The basic process is straightforward. A user clicks a link. The server receives the request and executes the corresponding PHP file. The code can query a database — for example: “Which items did this user order yesterday?” PHP inserts the database’s response into an HTML template and sends back the finished document. Every page view can thus be individual and up to date.

PHP code is written in plain text files with the .php extension and is mixed together with HTML. A simple example: a file contains ordinary HTML for the page header, then a PHP block that calculates and outputs the current day of the week, then ordinary HTML again. The server only interprets the PHP blocks; everything else it passes through unchanged.

This sets PHP apart from languages like JavaScript, which by default runs in the user’s browser. Both can enable the modern web, but PHP controls what the server does — JavaScript controls what happens on the screen. In many web projects, the two work together.

PHP in products and news

Anyone running a blog on WordPress uses PHP every day — without noticing it. Every page viewed, every comment, every login is processed by PHP code. Shop systems like WooCommerce and the forum software phpBB are also built on PHP. In practice, the term comes up most often when security vulnerabilities are reported in WordPress plugins: these are almost always written in PHP.

PHP makes tech news whenever new versions of the language are released. PHP 8, released in 2020, brought significant speed improvements and new language features. Critics long considered PHP a poorly designed language; since version 7, that perception has noticeably improved, and the language is now taken more seriously within the developer community than it used to be.

For someone wanting to learn web development, PHP is a sensible starting point. The basic concepts — variables, loops, database queries — quickly translate into visible results. And once you understand how a PHP page comes together, you also understand the basic principle behind virtually every dynamic website.