What is the significance of using single quotes around array keys in PHP?

Using single quotes around array keys in PHP is significant because it ensures that the key is treated as a string literal. This is particularly important when the key contains special characters, spaces, or starts with a number, as PHP may interpret it differently without the quotes. By enclosing the key in single quotes, you can avoid any potential parsing issues and ensure that the array key is interpreted correctly.

$array = ['key with space' => 'value']; // Incorrect way without single quotes
$array = ['key with space' => 'value']; // Correct way with single quotes