Arduino Uno R3

The Arduino UNO R3 is a microcontroller board based on the ATmega328. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. Arduino UNO differs from all preceding boards because it does not use the FTDI USB-to-serial driver chip.

Additional features coming with the REV3 version are:

• ATmega16U2 instead of 8U2 as USB-to-Serial converter.
• 1.0 pinout: added SDA and SCL pins for TWI communication placed near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields to adapt to the voltage provided from the board and the second one is a not connected pin, that is reserved for future purposes.
• Stronger RESET circuit.
• Made in Italy

Find here more informations (including the tech specs) about the Arduino Uno.
"Uno" means "One" in Italian and is named to mark the release of Arduino 1.0. The Uno and version 1.0 are the reference versions of Arduino. The Uno is the reference footprint model for the Arduino platform.