PHPMaster.com has a new article for those new to the PHP language posted this morning - an introduction to using functions and making your code more reusable.
Let's start by defining the word "function." A function is a self-contained piece of code which carries out a particular task (or function!). A key benefit of using functions is that they are reusable; if you have a task that needs to be performed a number of times, a function is an ideal solution. They can be either defined by you or by PHP (PHP has a rich collection of built-in functions). This article will focus on programmer-defined functions but will touch briefly on PHP's functions to complete the picture.
They include a few code snippets showing the syntax of functions (including their name, arguments and returning a value). They suggest grouping your functions together in your code for easier maintenance and share a handy tip on making a function accept a varying number of arguments.