How can PHP developers effectively use the Syntax Highlighter geshi to only highlight specific code within a tutorial entry?

To only highlight specific code within a tutorial entry using Syntax Highlighter geshi, PHP developers can wrap the code they want to highlight in specific HTML tags with a class that geshi recognizes. By doing this, geshi will only highlight the code within those specific tags.

<div class="geshi">
    <pre>
        <code class="language-php">
            <?php
                // Code to be highlighted
            ?>
        </code>
    </pre>
</div>