Naturally, you know where a good deal of your personal data is: it’s on your mobile phone, tablet, and PC. The rest of it is in the cloud somewhere. Some of it is held by government organizations, educational and health care organizations. Some is held by banks, insurance companies, and stores like Wall Mart and Target. Some is held by social network sites like Facebook and Linkedin, or by e-commerce sites like Amazon. Most websites that you visit are storing some of your personal data.
Many of these organizations, particularly social networks and search engine businesses will claim that you are trading the use of your data for the services they provide, although they rarely provide any detail of what they are doing with your data. For example, if you send a specimen of your saliva to a genetic analysis company that traces your ancestry, they do not tell you that they may also sell your data to pharmaceutical companies. This happens.
Additionally, there are data brokers who gather your personal data from publicly available sources: court cases, marriage records, property records, etc. and combine it with other personal data they buy: browsing history, social media data and anything else they can get their hands on, including data from retail stores and even the Department of Motor Vehicles. They sell such data to anyone who is willing to bid for it.