Arduino Uno is a microcontroller board based on the ATmega328P. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator (CSTCE16M0V53-R0), a 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.. You can tinker with your Uno without worrying too much about doing something wrong, worst case scenario you can replace the chip for a few dollars and start over again.

Specifications:

Microcontroller	ATmega328
Operating Voltage	5V
Supply Voltage (recommended)	7-12V
Maximum supply voltage (not recommended)	20V
Digital I/O Pins	14 (of which 6 provide PWM output)
Analog Input Pins	6
DC Current per I/O Pin	20 mA
DC Current for 3.3V Pin	50 mA
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

Documents:

Package Includes:

1 x Arduino Uno Rev3

Controller Specifications
Family Name	ATmega328
GPIO Pins	14 Digital Pins 6 Analog Pins
Clock Speed	16 MHz
Operating Voltage	5V
DC Current per I/O pin	20 mA
DC Current for 3.3v Pin	50 mA
Memory Specifications
RAM	SRAM 2 KB (ATmega328)
Flash	32 KB (ATmega328) of which 0.5 KB used by bootloader