Online-only files, also called smart files, are a special kind of SkyDrive file in Windows 8.1 and Windows RT 8.1. You can browse them on your PC, but the file contents are really in SkyDrive, so they don’t take up much of your disk space. Online-only files look like normal files on your PC, they have all the typical file info (like date modified, file type, and size), and you can search them. When you open online-only files from File Explorer and most applications, the file contents are downloaded automatically.
If you're not connected to the Internet, you can browse thumbnails of online-only files, but you can't open or edit the full file. If you want to be able to open and edit a file offline, you need to make the file available offline while you're still connected to the Internet. This downloads the file contents to your PC, and keeps the file linked with SkyDrive online storage so that any changes you make from any device automatically appear everywhere when you reconnect to the Internet.
For info about making files available offline, see Getting to files when you're offline.
If you have Access all files offline turned on and run out of disk space, you need to first turn off this setting before you can make files online-only to free up disk space.
If you have multiple PCs, a file can be online-only on one PC and available offline on another. Any files you've added to SkyDrive from your PC or previously opened on your PC are automatically available offline on that PC. Any files you created on the SkyDrive website or added to SkyDrive from another device are online-only on your PC.
We don't recommend working with online-only files in a command prompt or using Windows PowerShell or other command-line tools.
Some actions might result in errors or even cause file contents to be deleted.