Few devices know more personal details about people than the smartphones in their pockets: phone numbers, current location, often the owner's real name—even a unique ID number that can never be changed or turned off.
These phones don't keep secrets. They are sharing this personal data widely and regularly, without users' awareness or consent.
In the world of mobile, there is no anonymity,
Smartphone users are all but powerless to limit the tracking. With few exceptions, app users can't "opt out" of phone tracking, as is possible, in limited form, on regular computers
IPhone and Android Apps Breach Privacy - WSJ.com