I think it is called "SyncToy"
DO NOT use SyncToy, when I tried it it left havoc... free or not it is not reliable.
Try
SyncbackSE it's the best $25 you'll ever spend for backup software. It's 25 for up to 5 pcs at your house. Of course you can try it for like 30 days.
It's incredibly fast and reliable, will show you what it's about to do before doing it, give you a deatiled report in html format etc.
I update my 30,000 track library in about 10-15 minutes depending on what changed.
I use Syncbackse to backup to a 2nd read only share for my kids to use, then to an external WD Mybook when I do major cleanup etc.. .then I disconnect the Mybook drive so it does not get used, or touched by surges, viruses etc. I'm thinking of keeping that drive at my office.