The Arduino UNO is the best board to get started with electronics and coding. If this is your first experience tinkering with the platform, the UNO is the most robust board you can start playing with. The UNO is the most used and documented board of the whole Arduino family.

Arduino Uno is a microcontroller board based on the ATmega328P (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 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. 

Technical specification of Arduino UNO board

MICROCONTROLLER ATmega328P

OPERATING VOLTAGE 5V

INPUT VOLTAGE (RECOMMENDED) 7-12V

INPUT VOLTAGE (LIMIT) 6-20V

DIGITAL I/O PINS 14 (of which 6 provide PWM output)

PWM DIGITAL I/O PINS 6

ANALOG INPUT PINS 6

DC CURRENT PER I/O PIN 20 mA

DC CURRENT FOR 3.3V PIN 50 mA

FLASH MEMORY 32 KB (ATmega328P) of which 0.5 KB used by bootloader

SRAM 2 KB (ATmega328P)

EEPROM 1 KB (ATmega328P)

CLOCK SPEED 16 MHz

LED_BUILTIN I/O 13

LENGTH 68.6 mm

WIDTH 53.4 mm

WEIGHT 25 g