.USERTILE-MS File Extension
File TypeWindows 8 User Tile File
What is a USERTILE-MS file?
File used by the developer preview and release preview of Windows 8, and replaced by the .ACCOUNTPICTURE-MS format in the final Windows 8 release; saves the "user tile," which is the user's image that appears on the Start screen; often contains a stock image or a picture taken with the computer's webcam.
USERTILE-MS files are saved to the C:\Users\[user]\User Tiles\ directory. They are saved in a proprietary format and cannot be viewed with a standard image viewer.
NOTE: Microsoft referred to user account pictures as "user tiles" until the official Windows 8 release, at which point they referred to them as "account pictures."