Short Tutorial/FAQ – What Is Cross-Device Tracking?

Question: I've noticed that after mentioning a product while my phone is near me, I'll start seeing ads for that product across my devices. What's going on?

Answer: Chances are, you were hit by cross-device tracking. This is a method of tracking users across multiple devices by leveraging ultrasonic tones — usually between 18-22 kHz — which are sound waves above the human hearing range that can be transmitted from one device to another through the air.

The primary goal of cross-device tracking is to gather a comprehensive view of a user's online activity across different devices. This allows for more targeted advertising, personalized content, and other services. Marketers love this technology because it's invisible and almost no one's blocking it yet. Unlike cookies, ultrasonic cross-device tracking doesn't ask users for permission.

Because of the lack of transparency and privacy issues, the FTC and cybersecurity experts are concerned about cross-device tracking. You can expect to hear more about this topic as time goes on.