Did you know that, as of 2018, around 83% of websites (where the language could be determined) base on PHP? That is definitely not bad for a language being created in 1995. You may ask yourself why. The reason is, that PHP is very simple for newcomers to learn but still manages to offer a lot of possibilities for experienced programmers. Furthermore it develops and supports its active open source community continuously.
PHP's versatility and ease allowed some very well-known websites like Facebook and Wikipedia to grow in the way they have.