Simply put, the Raspberry Pi is a low end computer. It doesn’t have any secret technology. It wasn’t put together by NASA. It doesn’t have MIT patents. It was the idea of four guy from the University of Cambridge’s Computer Laboratory to put affordable computes into the hand of kids to help them learn how to program.
Based on off-the-shelf parts, the Raspberry Pi is a credit=card sized computer that is designed to be tinkered with. Plug in a USB keyboard and mouse and a HDMI display and it will start Linux. It doesn’t boast high speed or a great graphics but it does offer low cost and the ability to ‘add’ features and hardware (to hack it). See the hardware pages for detailed information about how to add hardware.