We can program on Arduino UNO by using Arduino IDE (Integrated Development Environment) software. You can use the USB cable to connect Arduino UNO to your computer.

Arduino has announced the new UNO R4 board family for prototyping and learning. The new models feature a faster microcontroller, a USB-C connector, improved power, Wi-Fi and Bluetooth LE, and more.

The idea early on was to leverage existing Arduino libraries to connect with a standard USB mouse, specifically, the hardware would take the form of an Arduino Mega 2560 with a USB Host Shield.