What are some common challenges faced by PHP developers when generating dynamic HTML content from templates and data?

One common challenge faced by PHP developers when generating dynamic HTML content from templates and data is properly escaping user input to prevent cross-site scripting attacks. To solve this issue, developers should always sanitize and validate user input before inserting it into the HTML output.

// Example of sanitizing user input before inserting into HTML output
$user_input = "<script>alert('XSS attack!');</script>";
$sanitized_input = htmlspecialchars($user_input, ENT_QUOTES);
echo "<p>User input: $sanitized_input</p>";