A thermostat learns your schedule. A doorbell streams video to your phone. A factory sensor alerts maintenance before a machine fails. These are examples of the Internet of Things — networked physical devices embedded with sensors and software. They collect data, share it, and often act on it.

The term was coined by Kevin Ashton in 1999. Early IoT was industrial: RFID tags in supply chains, sensors in power plants. Consumer IoT arrived with smart speakers, lights, and watches. Today, billions of devices are connected. Estimates vary, but the number keeps climbing.

Common applications

• Smart home: lights, locks, thermostats
• Wearables: fitness trackers, medical monitors
• Industry: predictive maintenance, asset tracking
• Agriculture: soil sensors, livestock monitors
• Cities: traffic lights, parking meters, air quality

IoT security is a mess. Many devices ship with default passwords. They rarely get updates. A compromised camera can be recruited into a botnet. Convenience and risk arrive in the same package.