SyncToy is a file syncing tool made by Microsoft. It has not been updated for quite some time, but really doesn't need it other than maybe an aesthetic overhaul. I use it to backup things from my PCs to my NAS.

This page is somewhere I can point poeple when they want someway to automate backing up to an external drive or NAS, but traditional back-up software is too cumbersome of vague. Which has been my experience. SyncToy can get a tad granular, but it really is an all or nothing sync solution.

https://www.microsoft.com/en-us/download/details.aspx?id=15155

Once installed, you need to create a folder pair. Each folder pair represents a back-up 'job'. The pair is divided into a LEFT folder and RIGHT folder. The left folder will almost always be the local folder you are wanting to backup. The RIGHT folder is the backup destination.

So your LEFT folder might be your Documents folder in your Windows user profile.

And your RIGHT folder might be a folder on an external drive that you want backup your Documents to.

When setting up a folder pair, you will be asked what you want to do with this pair. The options are as follows: Synchronize, Echo, and Contribute. The program provides a rather concise description of each option, but I will elaborate a little on each one.

Synchronize will do just that. It will synchronize all changes made to either side of the folder pair to the other side. This If you create a file on the LEFT, it will add it to the RIGHT. If you Then delete a file on the RIGHT, it will delete it on the LEFT.

This option is good if you work on projects on a couple different machines, but you can't necessarily for on them from a share and need the files local. This option will be less and less needed with the advent of cloud syncing services (Dropbox for example), but there are a few workflows that might be aided by it.

Echo will likely be the option you want. It will only work from LEFT to RIGHT. Any changes on the LEFT will be reflected on the RIGHT. But you can always manipulate or add items on the RIGHT that will not be reflected LEFT.

The only downside to this option in 'backup' terms is that it will not save you from accidentally deleting something. But that is where the next option comes in

Contribute works similar to Echo, except that it ignores the deletion of files altogether. Depending on what kind of data you are dealing with, this is really the true 'backup' option.