An I/O device is a hardware mechanism that generates or consumes data, allowing a computer system to interact with the external world. I/O devices connect to the system through I/O controllers.

Common examples include:

• Input devices: keyboard, mouse, touchscreen
• Output devices: monitor, printer, speakers
• Storage devices: hard disk, SSD, USB drive
• Network devices: Ethernet adapter, Wi-Fi card
• Imaging devices: camera, scanner