The Arduino UNO is one of the most popular and widely used microcontroller development boards in the Arduino family. It is based on the ATmega328P microcontroller and is designed to be beginner-friendly while powerful enough for intermediate and advanced projects. The board typically comes in the Arduino UNO R3 version, which is the most common. It has 14 digital input/output pins (6 of which can be used as PWM outputs), 6 analog input pins, and operates at 5V logic level. The board is powered either through a USB Type-B cable (from a computer) or an external power supply (7–12V recommended). The UNO runs at a clock speed of 16 MHz, has 32 KB of flash memory for storing programs, 2 KB of SRAM, and 1 KB of EEPROM. It also includes a USB-to-serial converter (ATmega16U2 or CH340 in clones) that allows easy programming via the Arduino IDE. Because of its simplicity, versatility, and large community support, the Arduino UNO is ideal for learning microcontrollers, prototyping electronic circuits, and developing IoT or robotics projects. It can be used to control sensors, LEDs, motors, displays, and other hardware components with ease.