Описание тега bootcompleted
ACTION_BOOT_COMPLETED is one of the standard actions in Android OS that Intent defines for receiving broadcasts. It is broadcasted once after the system has finished booting.
ACTION_BOOT_COMPLETED is one of the standard actions in Android OS that Intent defines for receiving broadcasts. It is broadcasted once after the system has finished booting. It is usually used to perform some sort of initialization in application (creating alarms is a common usage case). You must hold the RECEIVE_BOOT_COMPLETED permission in order to receive this broadcast. This is a protected intent that can only be sent by the system.
Information is taken from Android Developers site.