Arduino Uno is an open-source microcontroller board based on the ATmega328P microcontroller chip. It has 14 digital input/output pins, 6 analog inputs, a 16 MHz quartz crystal, a USB connection, a power jack, and a reset button. The board can be programmed with the Arduino software, which is a simplified version of the C++ programming language. The Arduino Uno is commonly used in electronics projects and is popular among hobbyists and professionals alike due to its low cost, ease of use, and versatility. It can be used to control lights, motors, sensors, and other electronic components, and can be integrated with other devices and technologies to create complex systems.