References are a very useful part of PHP and, for that matter, most other programming languages. However, references can be somewhat confusing when you first start learning about them.
This tutorial is a gentle introduction to references in PHP. You find out what references are, and how they work. You learn how to create and delete references, as well as pass references to and from functions. You also explore some other uses of references, and discover situations where PHP creates references automatically on your behalf.