Much of the data and personal information that tech companies collect comes from the user directly, like entering your name, email address, and phone number on your Facebook page. Companies also collect data from your device’s unique identifiers, your activity on third-party sites and applications, GPS, sensor data from your device, and information about things near your device like cell towers, Bluetooth-enabled devices, and Wi-Fi access points. Finally, companies get personal data from publicly accessible sources like local newspapers, third party marketing partners, and advertisers and in some cases, credit bureaus.