Online-only files, also called smart files, are a special kind of OneDrive file in Windows 8.1 and Windows RT 8.1. You can browse them on your PC, but the file contents are really in OneDrive, 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 aren't 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 OneDrive online storage, so that any changes you make from any device automatically appear everywhere when you reconnect to the Internet.
Swipe down or right-click the file or folder to select it, then tap or click Make offline. If you're worried about using too much space on your PC, make fewer files available offline, or if there are files you don’t need to use when you’re offline any more, change them back to online-only.
If space on your PC isn't a concern, you can also make your entire OneDrive available offline:
Swipe in from the right edge of the screen, then tap Settings.(If you're using a mouse, point to the bottom-right corner of the screen, move the mouse pointer up, then click Settings.)
Tap or click Options, then turn on Access all files 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. For information about making all files online-only to clear some disk space, see Tips for freeing up drive space on your PC.
Press and hold or right-click the file, then choose Make available offline. To make your entire OneDrive available offline, press and hold or right-click OneDrive in the left pane, then choose Make available offline.
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 OneDrive from your PC or previously opened on your PC are automatically available offline on that PC. Any files you created on the OneDrive website or added to OneDrive 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.