Computer peripherals are external devices that connect to a computer to enhance its functionality. They can be categorized into input devices, like keyboards and mouses, which allow users to interact with the computer, and output devices, such as monitors and printers, which display or produce information. Additionally, there are storage peripherals, like external hard drives and USB flash drives, that provide extra space for data. Networking peripherals, such as routers and modems, enable internet connectivity. Together, these devices expand what a computer can do, making it more versatile and user-friendly.