Backup term is related to the Database of computer system which is more powerful technique that is used for to store the shadow copies of original data refers to the process of making copies of data or data files to use in the event the original data or data files are lost or destroyed. Secondarily a BackUp may refer to making copies for historical purposes, such as for longitudinal studies, statistics or for historical records or to meet the requirement   s of a data retention policy. Many applications, especially in a Windows environment, produce BackUp files using the .BAK file extension. Backup is the activity of copying files or databases so that they will be preserved in case of equipment failure or other catastrophe. Backup is usually a routine part of the operation of large businesses with mainframes as well as the administrators of smaller business computers. For personal computer users, backup is also necessary but often neglected. The retrieval of files you backed up is called restoring them.