Cortana
Cortana is your personal assistant. Cortana works best when you sign in and let it learn about you and your activities by using data from your device, your personal Microsoft account, third-party services and other Microsoft services. To help Cortana to provide personalised experiences and relevant suggestions, you can let Microsoft collect and use 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 who you interact with on your device. When you are signed in, Cortana also learns about you by collecting data about how you use your device and other Microsoft services, such as your music, alarm settings, whether the lock screen is on, what you view and purchase, your browsing in Microsoft Edge and Bing search history, and more. You can manage what data Cortana uses, and what it knows about you in Cortana Settings, Notebook and Permissions. You can always sign out of Cortana, and when you do, Cortana will still be there to help, but your experiences will not be personalised. 

Learn more about Cortana in the Privacy Statement (http://aka.ms/privacy) and in the Cortana Learn more (http://aka.ms/cortanafaq)