What are the potential pitfalls of using PHP to modify title tags for SEO purposes?

One potential pitfall of using PHP to modify title tags for SEO purposes is the risk of introducing errors or inconsistencies in the titles. To avoid this, it is important to carefully validate and sanitize any input that is used to generate the title tags. Additionally, it is crucial to ensure that the PHP code is properly structured and error-handling mechanisms are in place to catch any issues that may arise.

// Example of sanitizing and validating input for title tag modification
$title = isset($_GET['title']) ? htmlspecialchars($_GET['title']) : 'Default Title';
echo "<title>$title</title>";