The 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.
The Uno is a microcontroller board which 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.
The Uno differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega16U2 (Atmega8U2 up to version R2) programmed as a USB-to-serial converter.
Microcontroller : ATmega328P
Operating Voltage : 5V
Input Voltage (recommended) :7-12V
Input Voltage (limits) : 6-20V
Digital I/O Pins : 14 (of which 6 provide PWM output)
Analog Input Pins : 6
DC Current per I/O Pin : 40 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
1 x UNO R3
1 x USB cable