Arduino Micro is the smallest board of the family, 

easy to integrate it in everyday objects to make them interactive.

The Micro is based on the ATmega32U4 microcontroller featuring 

a built-in USB which makes the Micro recognisable as a mouse or keyboard.

The Micro is a microcontroller board based on the ATmega32U4 (datasheet), 

developed in conjunction with Adafruit. It has 20 digital input/output pins 

(of which 7 can be used as PWM outputs and 12 as analog inputs), 

a 16 MHz crystal oscillator, a micro USB connection, an ICSP header, 

and a reset button. It contains everything needed to support the microcontroller;

simply connect it to a computer with a micro USB cable to get started.

It has a form factor that enables it to be easily placed on a breadboard. 

The Micro board is similar to the Arduino Leonardo in that 

the ATmega32U4 has built-in USB communication, 

eliminating the need for a secondary processor. 

This allows the Micro to appear to a connected computer as a mouse and keyboard,

in addition to a virtual (CDC) serial / COM port. 

t also has other implications for the behavior of the board;