https://www.businessinsider.com/apple-hires-chaos-monkeys-au...
The App Store has sponsored apps.
Apple News has ads in the app, before you click on any articles.
Apple Music/iTunes Store/Books has promoted artists/albums/movies/TV. It’s unclear whether any of these are paid promotions by the content producer but they’re in a banner so I have to assume Apple gets something out of it.
Apple Podcasts also has a featured section, likely paid ads.
And, as I mentioned, it’s extremely likely that Apple is working on a replacement for Yelp for Apple Maps, which will potentially be a big source of revenue.
And of course, there are ads for Apple’s own in-house TV+ content. Not an ad network, but if they know what you like they can better promote their TV shows. By default the TV app sends random push notifications.
The more Apple gets into content the more knowing your personality and interests is important to their business model.
