It's cloud storage.

Your files get backed up to the cloud.  The files can be accessed by any computer/tablet/phone that has internet access.

I have a local copy on my computer.  Any time a file is added, changed or deleted it synchronizes all local copies (you can have it on more than one computer) and the cloud backup

I think it's awesome.

Although I am not a fan of the subscription service I think the price is reasonable when you consider the benefits.

Jay