How to use SharedPreferences in android Studio to store and fetch values (Part 1)

SharedPreferences is an API from Android SDK to store and retrieve application preferences. SharedPreferences are simply sets of data values that stored persistently. Persistently which mean data you stored in the SharedPreferences are still exist even if you stop the application or turn off the device.
Interface for accessing and modifying preference data returned by getSharedPreferences(String, int). For any particular set of preferences, there is a single instance of this class that all clients share. Modifications to the preferences must go through an SharedPreferences.Editor object to ensure the preference values remain in a consistent state and control when they are committed to storage. Objects that are returned from the various get methods must be treated as immutable by the application.