A server side language that is used to present data, such as a webpage. Usually with the confines of HTML tags, but it doesn’t always have to work that way.
Specifically, it stands for “Personal Home Page”, as the creator of the language was writing a resume at the time and needed a way to present it.
However, an easy way to think of it is by what it’s become know for : “Pre Hypertext Processor”. This means that data is processed before any hypertext markup is processed. (which is true)
This small example will print to the screen “My name is Randy” :
<?php $name = 'Randy'; echo 'My name is ' . $name . ' '; ?>