Your devices are tracking you all the time. You just don’t know it yet.
When you consent to sharing your data with many popular apps, you’re also allowing app developers to collect your data and sell it to third parties through trackers that supply advertisers with detailed information about where you live, work, and shop.
In November 2017, Yale Privacy Lab detected trackers in over 75% of the 300 Android apps it analyzed. A March 2018 study of 160,000 free Android apps found that more than 55% of trackers tried to extract user location, while 30% accessed the device’s contact list. And a 2015 analysis of 110 popular free mobile apps revealed that 47% of iOS apps shared geo-coordinates and other location data with third parties, and personally identifiable information, like names of users (provided by 18% of iOS apps), was also provided.
These are particularly nasty trackers, since it’s generally more difficult to block them.