There's nothing to stop you from using a Briefcase to synchronize files remotely. For example, if you are using a VPN to connect to your home network, as I explain in Part V, you might want to synch the files in your Briefcase from time to time with the versions at home.
Pop-ups are browser windows that open while you are surfing the Internet, usually without your consent, usually advertising something. They are a nuisance. In contrast, spyware—programs placed on your computer without your informed consent that monitor your activities—can do actual harm (in addition to delivering information about your habits to third parties).
The general category of these kinds of software has been aptly called malware—because ...