In the end your smartphone use is helping to build up a picture of who you are and the kind of advertising you're interested in for companies like Google, Facebook, and others -- even if an app isn't part of a massive advertising network, it may well sell its data to one. Apple stands apart in this regard, keeping the data it tracks for its own use and largely on a single device, though of course the apps that run on iOS have more freedom to do what they want. Even if you're reasonably content to put up with some monitoring on Android and iOS, it's important to know what kind of data you're giving up every time you switch your smartphone on. Whether it means you uninstall a few social media tools, or disable location tracking for a few apps, it gives you some semblance of control over your privacy.
Mark Nield explains some ways that phones track users, including capturing location settings via photographs. He also provides some tips for how to regain some of the control through the privacy settings. Along with Adam Greenfield’s breakdown of the smartphone, these posts help to highlight what data is being gathered about us and how.