PHP is truly a defining technology of our age. For all the tongue-in-cheekiness of my comment, it’s a matter of fact that several giant web properties were built with PHP and have had irrefutable global impact.
It would lint every appearance of a ‘<?php’ token with the message ‘you wrote your code in a crappy language’.
Ok, well apart from Facebook and Wikipedia, what have the PHP team ever done for us?
Wordpress
Ok, well apart from Facebook, Wikipedia and Wordpress...
— After M. Python
Wordpress is PHP, which is over 20% of the web.
I'd say most web sites (millions) in the period between Web 1.0 and early 2.0 were PHP.
The historical reason for the transition from Perl to PHP was that PHP had a standard library with 3,000 functions and was fast enough, while Perl users needed to install CPAN modules, a problem in shared hosting, and mod_perl is very fast but is not intended for shared hosting.
I can also think of nichimen mirai which was also 10 years ahead of the competition in terms of ergonomics and features and was based on symbolics S-graphics system (and I kinda believe most of the value in mirai was due to the lisp broader paradigm, you could clearly see how limited most programs were at the time, exception being maybe prisms/houdini [which was probably C based though:)])
some people also quote apl or prolog to be an extensive reason on why their product exists or has an edge
Like a well known hospital, or casino: big static frontage, always remodeling.
(In addition to being like a building, Facebook is also like a chair.)