Let's keep it simple,
"When you turn-on a computer," the hardware
turns on... but it has absolutely nothing to do
. Its only purpose in life is "to run programs," and it's therefore absolutely useless without a program to run. Well... as a matter of fact, it does
have "a program to run," and that program is called an operating system
IBM used the term, "system control program."
And maybe that's a better term, because the sole purpose of an operating system is "to control the system," that is to say, the hardware. It creates the environment ... the foundation, as it were ... that every other program you might ever wish to use requires in order to do anything.
Microsoft Windows is such a program. Apple's OS/X is another. Linux is a third. (There are many more.) Take your pick.
As a user,
you probably don't even distinguish between "the computer" and "the operating system." To you,
"the hardware really doesn't matter at all." You turn on "the computer" and you use "Windows,"
exactly like you have always done. (Since you were, uhhh,
Linux, therefore, completely re-defines
what "the computer" is
it is utterly terrifying.
it is utterly liberating.