The arduino leonardo is a microcontroller board based on the atmega32u4 (datasheet). It has 20 digital inputoutput pins (of which 7 can be used as pwm outputs and 12 as analog 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 a ac-to-dc adapter or battery to get started.
The leonardo differs from all preceding boards in that the atmega32u4 has built-in usb communication, eliminating the need for a secondary processor. This allows the leonardo 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.
Summary
microcontroller : atmega32u4
operating voltage: 5v
input voltage (recommended): 7-12v
input voltage (limits) : 6-20v
digital io pins: 20
pwm channels: 7
analog input channels: 12
dc current per io pin: 40 ma
dc current for 3.3v pin: 50 ma
flash memory: 32 kb (atmega32u4) of which 4 kb used by bootloader
sram: 2.5 kb (atmega32u4)
eeprom: 1 kb (atmega32u4)
clock speed: 16 mhz

The arduino leonardo is a microcontroller board based on the atmega32u4 (datasheet). It has 20 digital inputoutput pins (of which 7 can be used as pwm outputs and 12 as analog 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 a ac-to-dc adapter or battery to get started.
The leonardo differs from all preceding boards in that the atmega32u4 has built-in usb communication, eliminating the need for a secondary processor. This allows the leonardo 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.
Summary
microcontroller : atmega32u4
operating voltage: 5v
input voltage (recommended): 7-12v
input voltage (limits) : 6-20v
digital io pins: 20
pwm channels: 7
analog input channels: 12
dc current per io pin: 40 ma
dc current for 3.3v pin: 50 ma
flash memory: 32 kb (atmega32u4) of which 4 kb used by bootloader
sram: 2.5 kb (atmega32u4)
eeprom: 1 kb (atmega32u4)
clock speed: 16 mhz