what is computer hardware ?

Definition :-  the physical parts of a computer and related devices. Internal hardware devices include motherboards, hard drives, and RAM. External hardware devices include monitors, keyboards, mice, printers, and scanners it all is colled hardware

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