Are there any specific rules or guidelines to follow when nesting PHP code within PHP code?

When nesting PHP code within PHP code, it is important to ensure that the nested code is properly enclosed within the appropriate opening and closing PHP tags. This helps to avoid syntax errors and maintain the readability of the code. Additionally, it is good practice to use proper indentation and spacing to clearly distinguish the nested code from the outer code.

<?php
// Outer PHP code
$variable = 10;

// Nested PHP code
if ($variable > 5) {
    echo "The variable is greater than 5.";
}
?>