The Arduino Leonardo employs a single ATMega32U4 MCU with a USB interface baked right in. Since no secondary USB-Serial converter IC is required, you can easily use the Leonardo to emulate arbitrary USB devices, such as a keyboard or mouse. The board has 14 digital input/output pins (of which 7 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, a USB micro B connection, a power jack, an ICSP header, and a reset button. You can learn more about the specifications of the Arduino Leonardo here. There are many compatible clones for the Arduino Leonardo available, including the Seeeduino Lite and the Pololu A-Star 32U4 Prime LV. You can use compatible clones interchangeably with the Leonardo for all the examples in Exploring Arduino.