The document discusses the Internet of Things (IoT), which refers to the network of physical objects embedded with electronics, software, sensors and connectivity that allows these objects to collect and exchange data. The document provides several examples of IoT applications such as parcel tracking systems, digital photo frames, smart payment cards, fitness trackers, and systems that provide real-time transit updates. It also describes how the Arduino board offers an accessible way for people to build basic IoT prototypes cheaply and discusses the author's personal experiences experimenting with IoT development.