This works on Windows as well as Macs. You can get a free version if you don’t want to backup too much stuff, or pay a few bucks a month for unlimited space.

Your data is valuable, so if you don’t have a proper backup solution (ie not just an external hard drive but some kind of off-site backup), then I urge you to try this or one of the many alternatives out there. This saved my ass…don’t wait until it’s too late!