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

I believe question was not whether you can call the static member of the class by calling ClassName::staticMember. Question was what's the difference between using self::classmember and $this->classmember.

For e.g., both of the following examples work without any errors, whether you use self:: or $this->

class Person{
    private $name;
    private $address;

    public function __construct($new_name,$new_address){
        $this->name = $new_name;
        $this->address = $new_address;
    }
}

class Person{
    private $name;
    private $address;
    public function __construct($new_name,$new_address){
        self::$name = $new_name;
        self::$address = $new_address;
    }
}