We will access, disclose and preserve personal data, including your content (such as the content of your emails, other private communications or files in private folders), when we have a good faith belief that doing so is necessary to.
Windows 10 will sync data by default including browser history, favorites and currently open web pages, as well as saved app, passwords and Wi-Fi network.
Microsoft voice assistant Cortana will also record every conversation as Microsoft’s new privacy statement points out:
“To enable Cortana to provide personalized experiences and relevant suggestions, Microsoft collects and uses various types of data, such as your device location, data from your calendar, the apps you use, data from your emails and text messages, who you call, your contacts and how often you interact with them on your device.”
Microsoft does allow Windows 10 users to opt out of privacy invasive features but what concerns privacy activists that users are opted in by default. Also Windows 10 generates a unique advertising ID for each user on each device allowing microsoft to profile each individual to serve commercial content and advertising.