Hardware is a comprehensive term for all of the physical parts of a computer, as distinguished from the data it contains or operates on, and the 
software that provides instructions for the hardware to acoomplish tasks.
The boundary between hardware and software is slightly blurry - 
firmware is software that is "built-in" to the hardware, but such firmware is usually the province of 
computer programmers and 
computer engineers[?] in any case and not an issue that computer users need to concern themselves with.
A typical computer (Personal Computer, PC) contains in a 
desktop or tower case the following parts:
-  Motherboard which holds the CPU, main memory and other parts, and has slots for expansion cards
 -  power supply - a case that holds a transformer, voltage control and fan
 -  storage controllers, of IDE, SCSI or other type, that control hard disk , floppy disk, CD-ROM and other drives; the controllers sit directly on the motherboard (on-board) or on expansion cards 
 -  graphics controller that produces the output for the monitor
 -  the hard disk, floppy disk and other drives for mass storage
 -  interface controllers (parallel, serial, USB, Firewire) to connect the computer to external peripheral devices such as printers or scanners
 
 See also 
 
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