Why: to help advertisers target people How #1: You have a smartphone, your smartphone has GPS, you have Twitter installed in your smartphone. Twitter requests

Why: to help advertisers target people How #1: You have a smartphone, your smartphone has GPS, you have Twitter installed in your smartphone. Twitter requests your location, you approve that request = done How #2: You have a smartphone, your smartphone has WiFi enabled. Your WiFi interface can see certain WiFi SSIDs. A Google car wardrived through your neighborhood saving all SSIDs of every Wifi and where they were last seen. Now location services has your location even with GPS disabled.