Arduino - ArduinoBoardUno
https://www.arduino.cc/en/Main/ArduinoBoardUno/
Arduino UNO & Genuino UNO. 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...
Arduino Uno - Wikipedia
https://en.wikipedia.org/wiki/Arduino_Uno
The Arduino Uno is an open-source microcontroller board based on the Microchip ATmega328P microcontroller and developed by Arduino.cc.
Arduino Uno Tutorial [Pinout]
https://diyi0t.com/arduino-uno-tutorial/
The Arduino Uno has a lot of different pins and therefore we want to go over the different kinds of pins. The Arduino Uno has in total 14 digital pins which provide a maximum current of 20 mA.
Arduino Uno Pin Diagram, Specifications, Pin Configuration...
https://components101.com/microcontrollers/arduino-uno
Find Arduino uno pin diagram, pin configuration, technical specifications and features, How to work with Arduino and getting started with Arduino Programming.