The mobile location industry began as a way to customize apps and target ads for nearby businesses, but it has morphed into a data collection and analysis machine.

Retailers look to tracking companies to tell them about their own customers and their competitors’. For a web seminar last year, Elina Greenstein, an executive at the location company GroundTruth, mapped out the path of a hypothetical consumer from home to work to show potential clients how tracking could reveal a person’s preferences. For example, someone may search online for healthy recipes, but GroundTruth can see that the person often eats at fast-food restaurants.

“We look to understand who a person is, based on where they’ve been and where they’re going, in order to influence what they’re going to do next,” Ms. Greenstein said.

https://www.nytimes.com/interactive/2018/12/10/business/location-data-privacy-apps.html?smid=tw-nytimes&smtyp=cur