Or, more properly, some apps are spying on you. WSJ has a disturbing article about how some apps pass key data to ad networks, including unique identifiers.
In theory, the iTunes app store policies require the app to ask permission, but many apps don’t, of course. Just an innocent oversight, y’know?
Of course, some people think it’s great.
Someone needs to start working on an app that disrupts/subverts those streams, stat.
Android has a couple of apps that do exactly that, though I can’t think of their names off the top of my head.