what is backup of data: A data backup is the result of copying or archiving files and folders for the purpose of being able to restore them in case of data loss.
Data loss can be caused by many things ranging from computer viruses to hardware failures to file corruption to fire, flood, or theft (etc). If you are responsible for business data, a loss may involve critical financial, customer, and company data. If the data is on a personal computer, you could lose financial data and other key files, pictures, music, etc that would be hard to replace.
why backup data: Backing up files can protect against accidental loss of user data, database corruption, hardware failures, and even natural disasters. It's your job as an administrator to make sure that backups are performed and that backup tapes are stored in a secure location.