Say Arduino five times fast
Arduino can sense the environment by receiving input from a variety of sensors and can affect its surroundings by controlling lights, motors, and other actuators. The microcontroller on the board is programmed using the Arduino programming language(based on Wiring) and the Arduino development environment (based on Processing). Arduino projects can be stand-alone or they can communicate with software running on a computer (e.g. Flash, Processing, MaxMSP).
The community of Arduino enthusiasts is vast, and includes region specific groups and special interest groups. The community is an excellent further source of assistance on all topics such as accessory selection, project assistance, and ideas of all sorts.