Peripheral devices are external hardware components that connect to a computer to enhance its functionality. Common examples include keyboards, mice, printers, and scanners. These devices allow users to input data, output information, or perform specific tasks that the computer alone cannot do. Peripheral devices can be classified into two main categories: input devices and output devices. Input devices, like microphones and webcams, allow users to send data to the computer, while output devices, such as monitors and speakers, display or produce results from the computer's processing.