iCloud is Apple’s solution for cloud-based computing. As far as I am concerned the best way to use iCloud is to activate it on all your Devices. That way you can pretty much access everything from every Device wherever you are. I think iCloud is secure so it is safe to do this. If you are an iCloud user, or only use it on some Devices, then read this article which explains how to access iCloud from ALL of Apple’s Devices and includes how to access it from Windows as well.