Given their integration into the Mac’s Finder, it can be easy to forget that online file sharing services like Dropbox, Google Drive, iCloud Drive, and Microsoft OneDrive can be accessed using a Web browser by anyone with your username and password. Obviously, you should always have strong, unique passwords, but to be safe, it’s best not to use services designed for public file sharing to store unencrypted files containing sensitive information like credit card numbers, Social Security numbers, passport scans, privileged legal documents, financial data, and so on. Keep such data secure on your Mac—outside of any synced folders—where accessing it requires physical access to the machine.