Under 'My Data' it stores Bing Searches and takes guesses as to your 'Interests'. How does it do that exactly? Operationally, how different is Outlook.com a.k.a Hotmail, compared to Google? Both are free, and nothing is for free in this world. So, Microsoft also have an angle.
Digging further you'll find information on Microsoft Advertising, which is something I don't remember actively opting in to, but I appear to be registered for: https://data.choice.microsoft.com/MyChoices/MSAdvertising
It states, and I quote:
> About Microsoft Advertising
> With the Microsoft Personal Data Dashboard (beta), you can choose not to receive personalized ads on websites that use the Microsoft Advertising Platform by not allowing Microsoft Advertising to use your information.
> Information used by Microsoft Advertising
> The Microsoft Advertising Platform customizes personalized ads based on different types of information, including but not limited to:
> Bing searches
> Interests
> Profile
> What does it mean not to allow Microsoft Advertising to use your information?
> Well, first, it doesn't mean you will stop getting ads or see fewer ads; but, it does mean that the ads you get won't be personalized anymore by Microsoft Advertising. Microsoft will continue to collect information for other uses, such as delivering content that is personalized for you; for example, the news articles displayed on MSN and the results you get when you search for software updates.
I guess, at least I can opt-out. Google doesn't allow me to opt-out of their creepiness. Saying that though, even though GMail creeps me out, but I'm addicted to the user interface.