Have you noticed when are using the Internet on your phone that the same ads follow you from site to site? It is possible to turn that tracking off. On the iPhone, go to Settings > Privacy and scroll down to Advertising. Turn "Limit ad tracking" to On (you want to see green). In Android, go to your Google Settings app (not your usual Android settings) and tap the Ads link. Then tap "Opt out of interest-based ads". For more on both platform phones and others see: How To Limit Spying on Your Phone Habits.