What are common pitfalls when using PHP includes?

Common pitfalls when using PHP includes include naming conflicts, security vulnerabilities, and performance issues. To avoid naming conflicts, use unique names for included files and variables. To prevent security vulnerabilities, avoid including files from user input and sanitize any input before including it. To address performance issues, consider using autoloading or caching mechanisms.

// Example of using unique names for included files to avoid naming conflicts
include 'header.php';
include 'content.php';
include 'footer.php';