The Arduino Micro is a special form of the new Leonardo board and uses the same ATmega32u4 processor with 20 digital I/O pins, of which 12 can be used as analog pins and 7 can be used as PWM output.
It has 32KB of flash memory and 2.5KB of SRAM.
The Micro was made for use on breadboards in the same way as the Mini but in a newer, updated form. But unlike the Mini, the Micro is a full-featured board complete with a USB connector.
And like Leonardo, it has built-in USB communication, allows the board to connect to a computer as a mouse or keyboard. Figure shows the Arduino Micro board.
Although branded as an official Arduino board, the Arduino Micro is produced in cooperation with Adafruit.