There is an option available in the iPhone which helps you to turn on the mood of do not disturb in your iPhone. This option is indicated with the symbol of the moon on your iPhone screen. These are the advancement in the iPhone operating system which makes them different from all other mobile phones and operating systems. It will help its customer to categorize an individual and somehow superior to others.
You can know in full detail about the Crescent Moon Icon On My iPhone: https://www.answerslave.com/crescent-moon-icon-iphone-remove/
The reasons why they claim that they are best. They are not using any common Android system which is used in every mobile and venerable in case of security. On the other hand, we have an iPhone with its own operating system. That will provide its user full grip on their data access. To ensure the data security iPhone operating system compromise on some operating option like you cannot use Bluetooth for transfer of files. But this will increase its working efficiency and control the damage of virus to device and operating system. Where they limit the working of some of their options to make security full proof they will add some options in their operating system which no one introduces before them.
Like the option of do not disturb mood, it will receive all your SMS and calls when it is on but did not even vibrate. There is a different category of these options which will be shown by different color and shapes of the moon on your mobile screen. If you are seeing a full moon in your status bar it means do not disturb mood is on. If you enable do not disturb mood for a particular contact you will see the sign of half moon against its message whenever you received his or her message. If this moon sign is blue it means you did not read the SMS of that contact which you mark in do not disturb option.