Which computer accessory is both an input and output device?

Computer accessories, or peripherals, are usually classified as input devices (which send data into the computer), output devices (which present results from the computer), or, in some cases, both at once.

A scanner is normally an input device on its own, since it captures an image or document and feeds that data into the computer. However, the question asks about a device that functions as both input and output, and among common accessories, the network card fits this description: a network interface card both receives data coming in from a network (acting as an input path into the computer) and sends data out from the computer onto the network (acting as an output path). This two-way flow of data through the same device is what makes it both an input and an output device.

A monitor is purely an output device, since it only displays information and cannot send data back for processing. A printer is also purely an output device, producing a physical copy of data. A standard scanner, likewise, only sends data into the computer and does not receive data back from it in the same operational sense.

Exam tip: to decide if a device is both input and output, check whether data genuinely flows in both directions through it during normal use.