Facebook users — 68% of American adults — volunteer their age, hometown and jobs, whether they have kids, where they vacation, whether they like "Duck Dynasty" or "Will and Grace," or asked for updates from a local Indivisible chapter or the local Republican Party. As you browse the internet, third-party data trackers can follow your internet activity and add other bits of data to compile a substantial dossier on each person.

Source: Los Angeles Times March 26, 2018 14:52 UTC