Many gurus will stress the importance of making backups of your blog or website in case your website is hacked or a “routine” software update goes wrong. This is excellent advice; particularly if you store the backups offline rather than in your webspace.
There is quite a range of software available which will do this automatically. Backup files can however be very large so many of these programs will create rolling backups which consist of, typically, the backups from each day of the last week. When they have created the backup on day 8 they delete the day 1 backup and then when they create the day 9 backup they delete the day 2 backup. This keeps the repository containing the stored backups at a managable size and ensures you have a weeks worth of the freshest daily backups.