A “peripheral” in terms of personal computing is any external device that provides input and output for the computer.
A common example might be a digital camera. A person may go on vacation and take a large number of photographs and want to transfer these files from their digital camera over to the hard drive on their computer for storage.
An even more common example is your computer keyboard. Have you ever had the experience of all of the sudden your keyboard stops working? Well, as we all know, usually it is just a matter of rebooting your computer. But sometimes special attention is required to install peripherals and keep them working.
Another good example is a PC game controller. It is not uncommon that on some PC games your controller does not respond. No need to purchase another controller! Peripheral support can have most devices working with whatever particular operating system and hardware is already in your home.