Arduino Uno is a microcontroller board based on the ATmega328 microcontroller. It is the most popular and widely used Arduino board, and is suitable for a wide range of projects. The Arduino Uno has 14 digital input/output pins, 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It operates on a voltage range of 7-20V and can be powered via the USB connection or an external power source. The Arduino Uno can be programmed using the Arduino Integrated Development Environment (IDE), which is a free software tool that allows users to write and upload code to the board. The Arduino Uno is widely used in DIY projects and in professional settings for tasks such as prototyping, data collection, and automation.