Which of the following is a common input device?

A keyboard is a common input device because it is specifically designed to allow a user to enter data into a computer system. Input devices are hardware that send data to the computer for processing, and keyboards facilitate this by providing a layout of keys for users to type letters, numbers, and other commands.

In contrast, a monitor, printer, and speaker are all output devices. A monitor displays visual output from the computer, a printer produces hard copies of documents or images, and a speaker outputs sound. These devices take information that has been processed by the computer and present it to the user in a particular format, whereas the keyboard’s primary role is to input data into the system. Understanding the difference between input and output devices is essential in recognizing how information flows within a computer system.