The Raspberry Pi is a credit card–sized computer that costs only US$35. It was originally developed to provide low-cost computers to schools and children, who couldn’t afford regular PCs or Macs. Since its release, the Raspberry Pi has been incredibly successful—as of this writing, selling over 25 million units. The Raspberry Pi has become the basis of a whole DIY movement with diverse applications, including home automation control systems, acting as the brain for robots, or linked together to build a personal supercomputer. The Pi is also a great educational tool.