There are essentially two aspects to this Book Backup service, the short term, which deals with backups in the past month and medium to long term data storage over months and years.

the short term
At any time Book Backup will keep all of the versions of any document you have created going back for a minimum of 30 up to a maximum of 60 days. Here’s how it works:

Say it is August 16th and you are working on a file you created on July 5th. Assume you have made changes to the file every day since it was created. Book Backup will now hold 43 different versions of that file. You wish to see the version you created on July 19th. You simply:

• go into Book Backup and click "previous backups"
• select July 19th
• search through backed up folders and files for that day and select the one you want to see
• click ‘Restore’

The file is returned to your computer. Book Backup rather cleverly took the original version of the file backed up on July 5th and combined that version with all the incremental changes you made in the intervening 14 days in order to produce and deliver the exact version you created on the 19th.

the medium/long term
At the end of August all incremental changes made during July will be consolidated with the original from July 5th. This ‘rolled up’ version of the file will then be kept as the base to which all incremental changes made during August can be added, so enabling restoration of every version of the file you created during August. At the end of September the process repeats, all August's changes being consolidated into a new ‘rolled up’ version of the file.

In this way the latest versions of backed up files are kept indefinitely along with a number of recent versions. For further details of the rollup process click here.