Microcontroller board based on the the ATmega328. For beginner and advanced users alike. If you are starting out with electronics, this is the board to get.
It has 20 digital input/output pins (up to 6 can be used as PWM outputs and up to 6 as analog inputs), a 16MHz clock, a USB connection, TWI, SPI, UART interfaces, a power jack, an ICSP header, and a reset button. Fully Arduino® compatible.
The board has all you need to get started, just plug in a USB cable or an AC/DC adapter and play!