section_path: Internet/Privacy and location-based services
section_name: Privacy and location-based services
paragraph_text: Privacy and location-based services
  
  Increasingly, mobile devices facilitate location tracking. This creates user privacy problems. A user's location and preferences constitute personal information, and their improper use violates that user's privacy. A recent MIT study by de Montjoye et al. showed that four spatio-temporal points constituting approximate places and times are enough to uniquely identify 95% of 1.5M people in a mobility database. The study further shows that these constraints hold even when the resolution of the dataset is low. Therefore, even coarse or blurred datasets confer little privacy protection.
  
  Several methods to protect user privacy in location-based services have been proposed, including the use of anonymizing servers and blurring of information. Methods to quantify privacy have also been proposed, to calculate the equilibrium between the benefit of obtaining accurate location information and the risks of breaching an individual's privacy.