How can PHP and HTML be effectively combined in code to ensure proper output and maintain HTML standards?

To effectively combine PHP and HTML in code, it is essential to use PHP to generate dynamic content within HTML templates. This can be achieved by embedding PHP code within HTML using PHP opening and closing tags. It is important to ensure that the generated HTML output complies with HTML standards to maintain proper structure and formatting.

<!DOCTYPE html>
<html>
<head>
    <title>Dynamic Content Example</title>
</head>
<body>
    <h1>Welcome, <?php echo $username; ?></h1>
    <p>Your account balance is: $<?php echo $balance; ?></p>
</body>
</html>