Apple and Microsoft have an in-house ad platform that is provided to, e.g. their app developers to use to monetize free apps, so people can be exposed to their

Apple and Microsoft have an in-house ad platform that is provided to, e.g. their app developers to use to monetize free apps, so people can be exposed to their ads there. Microsoft also runs ads on their free offerings, e.g. MSN News. I would expect Apple similarly runs ads on their free services.