<?php
$array1 = array(1, 2, 3);
$ref =& $array1[2];
// now $array[2] is a reference
var_dump($array1); // [2] => &int(3)
// this makes a copy of what's in $array1, not just the values within
// $array2[2] will be a copy *of the reference*
$array2 = $array1;
var_dump($array2); // [2] => &int(3)
// as such, changing the value of $array2[2] will also change $array1[2]
$array2[2] = 10;
var_dump($array1); // [2] => &int(10)