1) Storage of application data

— Database
— Files
— Prefrences
— Internal or Removable Storage
— Data backup services

2) Storing persistent data
— private accessible by your application only
— public accessible to other applications.
— how much space your data requires

3) Storage Options

— Shared Preferences - store private primitive data in key-value pairs
— Internal Storage - store private data on the device memory.
— External Storage - store public data on the shared external storage.
— SQLite Databases - store structured data in a private database.
— Network Connection - store data on the web site your own network server.

4) Android provides a way for you to expose even your private data to other applications — with a content provider. A content provider is an optional component that exposes read/write access to your application data, subject to whatever restrictions you want to impose.