PHP Classes: when to use :: vs. ->

Classes.php

<?php
/**
 * Simply put, :: is for class-level properties, and -> is for object-level properties.
 * If the property belongs to the class, use ::
 * If the property belongs to an instance of the class, use ->
 */ 

class Tester
{
  public $foo;
  const BLAH;

  public static function bar(){}
}

$t = new Tester;
$t->foo;
Tester::bar();
Tester::BLAH;

?>