PHP functions are similar to other programming languages. A function
is a piece of code which takes one more input in the form of parameter
and does some processing and returns a value.
You already have seen many functions like fopen() and fread() etc. They are built-in functions but PHP gives you option to create your own functions as well.
There are two parts which should be clear to you:
Creating a PHP Function
Calling a PHP Function
In fact you hardly need to create your own PHP function because there
are already more than 1000 of built-in...
