You register and get 2GB free storage area, visible in Windows Explorer as “dropbox”, alongside the existing “downloads”. There, you can drag files (from elsewhere) to some place such as the eisting Public folder or you can create a new folder and make it personal or sharable. If you make it sharable, you get prompted for an email address of the sharer. Dropbox then auto-sends an email to that address. The email includes a probably-unique secure (https) link (incorporating a big pseudorandom number) for them to click on. OK so it’s not just public. Great!