The document discusses the Raspberry Pi, a series of small single-board computers developed by the Raspberry Pi Foundation to promote computer science education. It provides details on the specifications of different Raspberry Pi models over time, how to set up a Raspberry Pi, and examples of projects that can be built with a Raspberry Pi like home automation, a voice-activated coffee machine, a weather station, and a home surveillance system. The Raspberry Pi uses an ARM processor and runs operating systems like Raspbian to function as a low-cost yet powerful computer that can interface with electronics and the physical world through its GPIO pins.