When to use self over $this?

Question

In PHP 5, what is the difference between using self and $this?

When is each appropriate?

Answer 1

self (not $self) refers to the type of class, where as $this refers to the current instance of the class. self is for use in static member functions to allow you to access static member variables. $this is used in non-static member functions, and is a reference to the instance of the class on which the member function was called.

Because this is an object, you use it like: $this->member

Because self is not an object, it's basically a type that automatically refers to the current class, you use it like: self::member