Output devices are devices that the computer sends information to in order to fulfil a task, examples of output devices are.

A monitor which displays the computers user interface and opens programs, allowing interacting.

A printer which prints paper documents. 

 
An input device is a device that is used by the user to control parts of the user interface and to insert information

An example of an input device would be a mouse which is used to move the cursor or a scanner which scans documents and converts them into digital format on a computer.