At a quarter-century old, PHP is one of those stalwart programming languages, widely used by web developers despite some much-publicized complaints (“a fractal of bad design,” in the words of one infamous blog posting) and, for much of its existence, a lack of formal written specification.

But TIOBE, which uses some controversial metrics to determine the popularity of various programming languages, thinks that PHP is on the decline—maybe even in a protracted death spiral. “Till the end of 2009 everything went fine, but soon after that PHP was going downhill from 10 percent to 5 percent market share in 2 years' time. In 2014 it halved again to 2.5 percent,” the organization wrote in a note accompanying its September update, which shows PHP falling from seventh to ninth place in the overall rankings.

Moreover, there’s apparently a reason for that decline of PHP. “From its start PHP was the Visual Basic for web design: easy to learn, easy to deploy, but mainly used by web designers with a limited software engineering background,” TIOBE added. “The downside of PHP's simplicity was that it was relatively easy to shoot security holes in it. PHP has been struggling with this for a long time.”

In order to create its rankings, TIOBE leverages data from a variety of aggregators and search engines, including Google, Wikipedia, YouTube, and Amazon. For a language to rank, it must be Turing complete, have its own Wikipedia entry, and earn more than 5,000 hits for +”<language> programming” on Google. That methodology has obviously sparked complaints that these rankings aren’t a “true” measure of languages’ respective popularity.

But that methodology also means that languages within TIOBE’s Top Ten tend not to move very much; there has to be a massive shift in search traffic. Java always seems in first place, followed by C, Python, and C++; if there is a shift in those upper echelons, it tends to be a one-place switcheroo. If PHP is consistently dropping, there might be something going on here.

Nonetheless, PHP remains a language in use by legions of web developers, so chances are very good it’s not going away anytime soon. If you’re curious about how it works and what it can do for your web-building, check out PHP 7.x; PHP 7.0 rolled out in 2015 and offers considerable speed and feature improvements. There are also tons of resources available online for continuing education.