How can PHP developers ensure portability of their projects by avoiding absolute file paths?

PHP developers can ensure portability of their projects by avoiding absolute file paths and using relative paths instead. This allows the project to be easily moved to different servers or directories without breaking file references. One way to achieve this is by defining a base path constant in a configuration file and using it to construct file paths throughout the project.

// Define base path constant in configuration file
define('BASE_PATH', dirname(__FILE__));

// Example usage in a PHP file
include(BASE_PATH . '/includes/header.php');