The Arduino Uno is a microcontroller board based on the ATmega328 chip. The Arduino Uno has 14 digital input / output pins (of which 6 can be used as PWM output), 6 analog inputs, a 16 MHz ceramic resonator, a USB connector, a power jack, an ICSP header and a reset button.
The Arduino Uno is by far the most popular development board for beginners and advanced. Because the ATmega328 is not soldered, it can easily be replaced when a catastrophic mistake is made. By buying this (original) version, the Arduino community is supported, so that new platforms can be developed.