Backup refers to copying of files or database of a computer data so it may be used to restore original after data loss event. we make backup of computer data so that if the computer will corrupt , we can restore data from backup files.
Booting is the process or set of operation that loads and hence start the operating system, starting from the point when user switches on the power button. A boot loader is a computer program which load operating system and other software .
Linux is free and open source software operating system. Operating system is a program which is used to run and manage electronic parts of computer system allow to run application program. We can change the source code of Linux operating system according to our requirement.
Crontab is a system daemon used to execute desired tasks at designated times. If the system is shutdown , when the job is scheduled , it is not executed . crontab is used to maintain crontab files for individual users . Each users can have their own crontab .