What potential issues can arise when including files in PHP, especially when dealing with paths and directories?

When including files in PHP, potential issues can arise with paths and directories. To ensure that the correct path is used, it's important to use absolute paths or properly handle relative paths. One common solution is to use the `__DIR__` magic constant to get the directory of the current file and then construct the path from there.

include __DIR__ . '/path/to/file.php';