The document discusses input and output devices used with computers. It describes input devices as those that enter raw data into the computer, like keyboards, mice, scanners, and sensors. Input devices are categorized as either manual, requiring human operation, or automatic, which input data without human involvement. Output devices are those that communicate the processed results from the CPU to the user, such as computer monitors, printers, speakers, and actuators that control real-world devices. The central processing unit processes input data and produces outputs that are easy for users to understand.