What can I keep when I upgrade?
What you can keep depends on the version of Windows you're running on your PC, so you'll only see the options available to you. Here's what you might see:
Windows settings
This keeps your settings such as Ease of Access, your desktop background, or Internet favourites and history. 
Personal files
This keeps any files that are saved in your User folder, such as your Documents and Desktop folders. 
Apps
This keeps apps that will work after you've upgraded. To get a report of which apps you currently have on your PC that will work, and those that won't, run the Upgrade Assistant, available online at http://go.microsoft.com/fwlink/p/?LinkId=261871 before you upgrade (you'll need to close Set-up to run the Upgrade Assistant). Some apps might work after you've upgraded but you'll need to reinstall them. You'll see a list of these in the report. You'll need your original installation media to reinstall them.
Note: If you're upgrading from Windows 7 to Windows 8.1, you won't see "apps" as an option of items to keep, and you'll need to reinstall your apps using the original installation media. 
Nothing
This deletes everything, including all of your apps, and replaces your current version of Windows with Windows 8.1. Your personal files will be moved to the windows.old folder. You can find more info online at http://go.microsoft.com/fwlink/?LinkID=12416.
If you choose Nothing, make sure you do the following before you continue:
•	Back up your files to an external hard drive, DVD or CD, USB flash drive or network folder.
•	Find the installation media or confirmation emails – if you bought programs online – for the apps that will work and will need to be reinstalled.
Note: If you use a fingerprint reader or another biometric device to sign in to your PC, make sure you write down your password. You'll have to enter your username and password the first time you sign in to Windows after upgrading to Windows 8.1.