https://techcrunch.com/2017/10/13/microsofts-windows-10-breaches-privacy-law-says-dutch-dpa/

The Dutch data protection authority has concluded that Microsoft’s Windows 10 operating system breaches local privacy law on account of its collection of telemetry metadata. The OS has been available since the end of July 2015.

Personal data being harvested by default by Microsoft can include the URL of every website visited if the Windows 10 user is browsing the web with Microsoft’s Edge browser (and has not opted out of full telemetry), as well as data about usage of all installed apps on their device — including frequency of use; how often apps are active; and the amount of seconds usage of mouse, keyboard, pen or touchscreen.