Array Syntax
The array syntax, or array notation, is the usage of square brackets after a data container, such as variables or properties, or a literal, to access an element. It is generally known to be used with array structures, though it may also be used with strings and objects.
<?php
$array = ['a', 'b', 'c'];
echo $array[1]; // b
$string = 'ABC';
echo $string[2]; // C
$object = new ArrayObject(['x', 'y', 'z']);
print $object[0]; // x
?>