How to track the smartphone apps that are tracking you

Fast Company:

When it comes to websites, we have ever more sophisticated techniques at our disposal to block the ads that sometimes track our wanderings around the internet. But most of us spend much of our time these days in mobile apps that offer no transparency on how we’re being tracked or sold–nor tools for blocking that behavior.

I don’t mind app tracking per se but I want to know which apps are doing it and be able to revoke that permission if I so choose.