Arduino Micro is the smallest board (48mm x 18mm) of the family, easy to integrate it in everyday objects to make them interactive.

The Micro is a microcontroller board based on the ATmega32U4 (datasheet),  developed in conjunction with Arduino.cc and 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. It also has other implications for the behavior of the board; these are detailed on the getting started page.

Features

ATmega32U4

The smallest board of the family

20 Digital I/O Pins, 32KB Flash Memory, 16 MHz Clock Speed

Be recognisable as a mouse or keyboard

Made in Italy