The Raspberry Pi is a credit card-sized computer with an ARM processor that can run Linux. This item is the Raspberry Pi Model A+, which has 256 MB of RAM, an HDMI output, audio output, RCA composite video output (through the 3.5 mm jack), one USB port, and 0.1″-spaced pins that provide access to general purpose inputs and outputs (GPIO). The Model A Raspberry Pis are smaller and less expensive than the Model B Raspberry Pis. The Raspberry Pi requires a microSD card with an operating system on it (not included). The Raspberry Pi is very popular, with lots of example projects and information available online.