A touchscreen is a device that works as both an input and an output device because it displays information (output) and allows users to interact with it by touching it (input). Other examples include headsets, which combine a speaker (output) and a microphone (input), and a modem, which sends and receives data to and from other devices.  
Examples of devices that are both input and output

• Touchscreens: Display information like a monitor, but also allow you to enter commands by touching the screen, as seen on smartphones, tablets, and ATMs. 
• Headsets: Include a microphone for capturing your voice (input) and speakers for playing audio (output). 
• Modems: Connect to the internet by sending and receiving data. 
• Network cards: Enable a computer to send and receive data over a network. 
• Facsimile (Fax) machines: Use a scanner to input a document and a printer to output a copy.