The Uno R3 without Cable is a micro-controller board base on the ATmega328 (datasheet). It has 14 digital input/output pins (of which 6 can be used as PWM outputs); 6 analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button.
It contains everything need to support the microcontroller; simply connect it to a computer with a USB cable or power it with an AC-to-DC adapter or battery to get started.
“Uno” means one in Italian and is the name to mark the upcoming release of Arduino 1.0. The Uno and version 1.0 will be the reference versions of Arduino, moving forward. The Uno is the latest in a series of USB Arduino boards and the reference model for the Arduino platform; for a comparison with previous versions, see the index of Arduino boards.
QUICK OVERVIEW
Micro-controller : ATmega328.
Operating Voltage : 5V.
Input Voltage (recommended) : 7-12V.
Digital I/O Pins : 14 (of which 6 provide PWM output).
Analog Input Pins : 6.