What is the difference between JSON output with and without array index in PHP?

When outputting JSON in PHP, including array indexes can provide additional structure and organization to the data. Without array indexes, the JSON output will simply list the values in the order they were added to the array. Including array indexes can make it easier to parse and manipulate the data on the receiving end. 

// JSON output without array index
$data = [
    "apple",
    "banana",
    "cherry"
];
echo json_encode($data);

// JSON output with array index
$data = [
    "0" => "apple",
    "1" => "banana",
    "2" => "cherry"
];
echo json_encode($data);

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