The device that allows a user to connect multiple USB devices to a single computer port is known as a USB hub. A USB hub expands the number of available USB ports, enabling users to connect devices such as external hard drives, printers, and keyboards. It facilitates easy connectivity without requiring multiple cables directly into the computer. Hubs can vary in design, offering features like power supply to charge devices or high-speed data transfer capabilities, making them essential for users with multiple USB peripherals.