The LEONARDO is an integrated USB HID board. Ideal for projects requiring the board to behave (act) as a USB human interface devices (keyboard, mouse, etc...).

The LEONARDO is a microcontroller board based on the ATmega32U4. It has 23 digital input/output pins (of which 7 can be used as PWM outputs and 12 as analogue inputs), a 16 MHz crystal oscillator, a micro 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 an AC-to-DC adapter or battery to get started (USB cable and power supply are not included).

Feature:
- Microcontroller: ATmega32U4 (16MHz)
- Input voltage: DC 7V~12V
- Regulator type (5V): LDO (linear)
- Output current: 5V=1A, 3.3V=800mA
- I/O: 23
- PWM: 7
- Analog inputs: 12
- USB connector: USB-B

and this Video Tutorial about Arduino LEONARDO will help start and make some simple Experiments with is it.