[[File:PDP-11-M7270.jpg|thumb|upright|[[PDP-11]] CPU board]]
'''Computer hardware''' includes the physical parts of a [[computer]], such as the [[central processing unit]] (CPU), [[Random-access memory|random-access memory]] (RAM), [[motherboard]], [[computer data storage]], [[graphics card]], [[sound card]], and [[computer case]]. It includes external devices such as a [[Computer monitor|monitor]], [[Computer mouse|mouse]], [[Computer keyboard|keyboard]], and [[Computer speakers|speakers]].<ref>{{cite web |title=Parts of computer |url=http://windows.microsoft.com/en-us/windows-vista/parts-of-a-computer |publisher=Microsoft |access-date=5 December 2013 |url-status=live |archive-url=https://web.archive.org/web/20131127145607/http://windows.microsoft.com/en-US/windows-vista/Parts-of-a-computer |archive-date=27 November 2013 |df=dmy-all }}</ref><ref>{{Cite book |last=Gilster |first=Ron |url=http://archive.org/details/pchardwarebeginn00gils |title=PC hardware : a beginner's guide |date=2001 |publisher=New York; London : McGraw-Hill |others=Internet Archive |isbn=978-0-07-212990-8}}</ref>
By contrast, [[software]] is a set of written instructions that can be stored and run by hardware. Hardware derived its name from the fact it is ''[[Hardness|hard]]'' or rigid with respect to changes, whereas software is ''soft'' because it is easy to change.
