What is the significance of using $_REQUEST['link'] instead of $_REQUEST[link] in PHP code?

Using $_REQUEST['link'] instead of $_REQUEST[link] in PHP code is significant because it ensures that the value of the 'link' key is accessed as a string. When using $_REQUEST[link] without quotes, PHP will treat 'link' as a constant, which may lead to errors or unexpected behavior. By using $_REQUEST['link'], we explicitly specify that we are accessing the 'link' key in the $_REQUEST superglobal array as a string.

$link = $_REQUEST['link'];