A family of open single board microcontrollers from Arduino LLC that is used by hobbyists and engineers to build electronic products. Although all the components on Arduinos can be purchased separately, they are available on printed circuit boards from the company. They are programmed in the Processing/Wiring language.
The name comes from the bar in Ivrea, Italy where students of the Interaction Design Institute Ivrea met to create Arduino in 2005.
UNO and GEMMA Boards
The UNO (top) is the classic Arduino board with 20 I/O pins, USB and an Atmel 8-bit CPU. The GEMMA (bottom) is a wearable board with three I/O pins. (Images courtesy of Arduino LLC, www.arduino.cc)