What best practices should be followed when structuring file includes in PHP projects to avoid conflicts and errors?

When structuring file includes in PHP projects, it is best practice to use absolute paths or constants to avoid conflicts and errors. This ensures that the included files are always referenced correctly regardless of the current working directory.

define('ROOT_PATH', dirname(__FILE__) . '/');
include(ROOT_PATH . 'config.php');
include(ROOT_PATH . 'functions.php');