You need to be able to distinguish between the terms 'Backup' and 'Archiving'.

Backing up

Backing up your data is where you make a copy of what is on your system.  However, the original data is still left in place.  The back up can be stored somewhere separately and just used in case the original data gets corrupted or deleted, or the hard disk gets damaged/stolen.

The backup can be used to restore your data to an earlier version.  

The key point is that if you make a backup, you are not deleting or moving the original data - it stays in the same place.

Archiving

Archiving is where you want a copy of your data/records, but you no longer need to keep it on your system.  Once the data is archived, it is usually removed from the system and the archived copy is kept elsewhere. 

This frees up space on the hard disk or wherever the data was originally stored.