The Arduino Uno is a microcontroller board based on the ATmega328. 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 Uno differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega16U programmed as a USB-to-serial converter.
Features:
digital I/O pins: 14 (of which 6 provide PWM output)
analogue input pins: 6
contains: 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button
power supply: 6-20 V max. (adapter not included)
microcontroller: ATmega328
digital I/O pins: 14 (of which 6 provide PWM output)
DC Current per I/O pin: 40 mA
DC Current for 3.3 V pin: 50 mA
analogue input pins: 6
flash memory: 32 kB (ATmega328) of which 0.5 kB used by bootloader
SRAM: 2 kB (ATmega328)
EEPROM: 1 kB (ATmega328)
clock speed: 16 MHz