USB devices are electronic gadgets that connect to computers and other devices using a Universal Serial Bus (USB) interface. They allow for data transfer and power supply between devices, making it easy to connect peripherals like keyboards, mice, and printers. USB devices come in various forms, including flash drives, external hard drives, and webcams. The USB standard has evolved over time, with different versions like USB 2.0, USB 3.0, and USB-C offering faster data transfer rates and improved functionality. These devices are widely used due to their plug-and-play capability, meaning they can be connected and used without needing complex installation processes.