Spotlight relies on metadata indexing to locate files quickly, but it intentionally excludes certain system files and hidden folders by default to prevent accidental modification or clutter. It won't find files stored on unmounted volumes or offline network drives. Spotlight also skips locations explicitly excluded by system settings or user privacy preferences. Differences from simple folder searches lie in its reliance on this pre-built index and defined exclusion rules.

For instance, files within the user's hidden ~/Library folder or on an ejected external hard drive won't appear in Spotlight results. Applications like Time Machine store local snapshots in folders typically excluded from indexing. Users working with developer tools or specific applications that store critical data in protected directories encounter this limitation frequently.

While exclusions protect system integrity and user privacy, this design choice limits file discovery for advanced users needing access to excluded locations. Users can manage excluded folders (System Settings > Sitemap & Privacy) to broaden searches, enhancing flexibility. However, limitations remain for very new files not yet indexed, severely corrupted files, or specific unsupported file formats, requiring manual browsing in Finder for complete assurance.