Seems to me Microsoft knows enough about me already, even though I turned off all the options to send stuff to Microsoft to 'improve your experience'. But that's another story.
It's pretty easy to restore a file from DropBox. The free software saves versions of your files for 30 days, and usually that's long enough if you have a system failure or something. You'll need to login to your Dropbox account and find deleted files. From there it's straight forward. If you accidentally delete a file, you can recover that, too. If it was on your hard drive, look in the recycle bin and recover it. If it was (say) a photo on an SD card or thumb drive, it won't be in the recycle bin, but it can be recovered. I deleted all the photos on an SD card recently, and recovered them. I described the process in detail here, so I won't repeat it.
So far, we've been talking about lost files. But there's another use for backup.
I'm working on a new project, and I'm about eleven thousand words in. But now I've decided I shouldn't have changed one of the early scenes. The story is coalescing in my mind, and the 'yes but' questions are bubbling to the surface. The changes I made don't work, so I want to go back to how the scene was written a number of days ago. I could restore the file to that date from Dropbox, but then I'd lose my current work. I could open an earlier version in Dropbox and find my deleted scene that way - but that means logging in to Dropbox, and if that version is more than 30 days old - it's gone.
When I start a new project I immediately create a file imaginatively entitled 'backup' under the project. Every day when I start work, before I do anything else, I copy my current file to backup and rename it with the date. eg WIP.docx is saved in backup as 170622 WIP.docx (ie yymmdd to keep the list in date order).
Later today I'm going to open the WIP from several days ago, copy the scene I want, and paste it into the current WIP. And since the project is in Dropbox, so are the backups - for double just in case.
For those interested in the project itself, the new book, currently titled 'Dryden 5', is set in the Dryden Universe, and kind of follows on from The Demon's Eye. It stars the same main characters, Tian Axmar and Brent Walker, with a solid supporting role for Admiral Ul-Mellor. It'll be done some time later this year.
And since Pip shows pictures of her chooks, maybe I can show pictures of my wild bird family. Just for something pretty to look at.