How can a PHP developer effectively navigate directory structures when including files?

When including files in PHP, developers can effectively navigate directory structures by using the `__DIR__` magic constant to reference the current directory of the file being executed. This allows for more robust and portable file includes, as it eliminates the need for hardcoded paths which can break when moving files around.

// Example of including a file using __DIR__ to navigate directory structures
include __DIR__ . '/includes/config.php';