All computer components can be divided into 5 categories.
Input Devices - any device that allows the user to put information into the computer. (e.g. keyboard, mouse, microphone, scanner)
Output Devices - any device that allows the computer to send information to the user. (e.g. monitor, printer, speakers)
Process - any device that converts or redirects information to another device. (CPU, motherboard, video/sound cards)
Power - any device that provides power to other devices. (power supply)
Storage - any device that stores information for any length of time. There are temporary storage devices (RAM) and permanent storage devices (Hard, floppy drives)
Permanent Storage Devices are like filing cabinets, they hold the information in an organized manner, but you have to search for it, to find it.
Temporary Storage Devices are like the desktop in an office. The information is close at hand, easy to find, but not organized, and you can't keep as much on your desk as you do in your filing cabinets. Also, temporary storage requires power to work. If you lose power, you lose everything you had stored in temporary memory!