PHP isn't quite as simple as HTML, in that, with HTML, you can
author a page and put it up on any number of host sites that let
you create webpages for free. HTML is ubiquitous.
PHP authoring, however, is more appropriate for someone running
a website from a server over which they have some control, since
PHP needs to be installed as a program on the server. You can do
this easily enough if you're running your own server. Optionally,
you would need to find a hosting site which has PHP installed on
THEIR servers. Free sites don't offer this functionality.
Many websites utilize pre-written PHP, rather than authoring their
own. Many Bulletin Boards are written using PHP, and are installed
as an application, such as Invision Power Board:
PHP is defined via this Google search:
"PHP is a recursive acronym for 'PHP Hypertext Preprocessor'.
It is an open source, interpretive, HTML centric, server
side scripting language. PHP is especially suited for Web
development and can be embedded into HTML pages."
Here's a manual on PHP, that includes sections on Getting
Started, Installation and Configuration, Language Reference,
Security, Features, Function Reference, and more:
And here's a basic tutorial in writing php, from the manual:
As you'll see, simple PHP can resemble simple HTML:
<?php echo '<p>Hello World</p>'; ?>
The difference is in the 'echo' function, which is interpreted
by the PHP program installed on the server, which then delivers
the appropriate results to the browser. There are numerous such
functions, called up by way of various tags in the PHP language.
PHP is thus ideal for creating database interactivity and dynamic
web content, while HTML is more for static pages.
I hope this satisfies your inquiry. If not, feel free to ask
Additional information may be found from an exploration of
the links resulting from the Google searches outlined below.
Searches done, via Google: