You walk up to your front door, and it unlocks as it recognizes the key fob in your pocket. It’s cold outside, but the air on the other side of your threshold is a toasty 74 degrees because the thermostat fired up your furnace the instant you (your phone, more accurately) crossed the 20-mile geofence you drew around your home. As the door swings open, your recessed lighting illuminates your path to the kitchen, everyone’s first destination when arriving home after a long day at work. A glance at an app on your phone, linked to the fitness tracker on your wrist, shows your daily calorie quota will accommodate a glass of wine with dinner.
It sounds like a scene from a sci-fi film script, but this vision of the future is attainable today, thanks to the concept of the Internet of Things: A world where every device—from the tiny sensors on your doors and windows to the largest home appliances—has an Internet address that renders it not only uniquely identifiable, but accessible from anywhere you have Internet access. And every one of these things can exchange messages with every other thing, no matter who built it.