# Application Data & Files

Android uses a file system that's similar to disk-based file systems on other platforms. The system provides several options for saving app data:

* **App-specific storage** - internal storage to saving sensitive information that other apps should not be able to access.
* **Shared storage** - storage for files that the app shares with other apps, including media, documents, and other files.
* **Preferences** - storage for private, primitive data in key-value pairs.
* **Databases** - storage for structured data in a private database using the Room persistence library.

|                                                                                                         | Type of content                                              | Access method                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | Permissions needed                                                                                                                                                                                                                                                                                                                                                  |
| ------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| [App-specific files](https://developer.android.com/training/data-storage/app-specific)                  | App-specific files                                           | <p>From internal storage, <a href="https://developer.android.com/reference/android/content/Context#getFilesDir%28%29">getFilesDir()</a> and <a href="https://developer.android.com/reference/android/content/Context#getCacheDir%28%29">getCacheDir()</a></p><p>From external storage, <a href="https://developer.android.com/reference/android/content/Context#getExternalFilesDir%28java.lang.String%29">getExternalFilesDir()</a> and <a href="https://developer.android.com/reference/android/content/Context#getExternalCacheDir%28%29">getExternalCacheDir()</a></p> | <p>Never needed for internal storage</p><p>Not needed for external storage when your app is used on devices that run Android 4.4 (API level 19) or higher</p>                                                                                                                                                                                                       |
| [Media](https://developer.android.com/training/data-storage/shared/media)                               | Shareable media files (images, audio files, videos)          | [MediaStore](https://developer.android.com/reference/android/provider/MediaStore) API                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | <p><strong>READ\_EXTERNAL\_STORAGE</strong> when accessing other apps' files on Android 11 (API level 30) or higher</p><p><strong>READ\_EXTERNAL\_STORAGE</strong> or <strong>WRITE\_EXTERNAL\_STORAGE</strong> when accessing other apps' files on Android 10 (API level 29)</p><p>Permissions are required for all files on Android 9 (API level 28) or lower</p> |
| [Documents and other files](https://developer.android.com/training/data-storage/shared/documents-files) | Other types of shareable content, including downloaded files | Storage Access Framework                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | None                                                                                                                                                                                                                                                                                                                                                                |
| [App preferences](https://developer.android.com/training/data-storage/shared-preferences)               | Key-value pairs                                              | [Jetpack Preferences](https://developer.android.com/guide/topics/ui/settings/use-saved-values) library                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | None                                                                                                                                                                                                                                                                                                                                                                |
| Database                                                                                                | Structured data                                              | [Room](https://developer.android.com/training/data-storage/room) persistence library                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | None                                                                                                                                                                                                                                                                                                                                                                |

## References

* [Android Developers: Data and file storage overview](https://developer.android.com/training/data-storage)