Every now and again someone asks about the folder Outlook creates in %localappdata%\microsoft\outlook named "gliding":
There is an empty folder called "gliding" in the same location as where the .pst files are stored. If I delete it the next time I open Outlook 2013 it just re-creates itself but it contains nothing.
Correct, if you delete the gliding folder (or any others in the Outlook folder), Outlook will recreate it. It's apparently used to push out or enable features (via an XML file) although, like you, I've never seen anything in it.
I know there are a lot of users who want to be in total control of their computer and don't want empty folders laying around, but you really shouldn't worry too much about any of the files or folders in the Outlook directory – these are support files used by Outlook. While you can delete them, Outlook will recreate the files as needed. The only files you need to concern yourself with is large orphaned cache files (.ost). Fortunately, Outlook 2013 and 2016 do a pretty good job of cleaning up these files when you delete accounts and you shouldn't have many of these hanging around either.
There is another new file you'll see in the Outlook directory, provided you have an Exchange Online account in your profile: a new data file with the extension .nst. This file caches the contents in the new Office Groups folders.