When an app is installed on the external storage:
- The .apk file is saved to the external storage, but any app data (such as databases) is still saved on the internal device memory.
- The container in which the .apk file is saved is encrypted with a key that allows the app to operate only on the device that installed it. (A user cannot transfer the SD card to another device and use apps installed on the card.) Though, multiple SD cards can be used with the same device.
- At the user's request, the app can be moved to the internal storage.
The user may also request to move an app from the internal storage to the external storage. However, the system will not allow the user to move the app to external storage if this attribute is set to internalOnly, which is the default setting.
Introduced in: API Level 8.