Researchers say Wi-Fi information can be used to figure out where a person is more than 90 percent of the time. Android applications such as Candy Crush Saga, Pandora and Angry Birds routinely collect it. Location data is seen as valuable for purposes such as advertising, where context-specific ads can be shown as a person moves into a certain area. Apple introduced in iOS 8 a method to make it more difficult to collect consistent data on devices, the study says. The researchers tracked 63 students over six months.”]
Source: https://www.csoonline.com/article/2927499/wifi-access-point-scans-can-betray-a-persons-location.html