Are there specific recommendations for organizing PHP code within HTML documents to maintain readability and facilitate future modifications or debugging?

To maintain readability and facilitate future modifications or debugging, it is recommended to separate PHP code from HTML markup by using PHP opening and closing tags within the HTML document. Additionally, organizing PHP code into separate functions or classes can help improve code structure and readability.

<?php
// Separate PHP code from HTML markup
$variable = "Hello, World!";
?>

<!DOCTYPE html>
<html>
<head>
    <title>PHP Code Organizing</title>
</head>
<body>
    <h1><?php echo $variable; ?></h1>
</body>
</html>