"Most computer users are aware of the existence of their hard
drive, even if they're not familiar with how it works. It's hard
not to be, since the first things people tend to ask when you get a
new computer are how much hard drive space you have, how fast the
machine is, and how much memory is included. From there, if you're
used to using Windows, then you've probably dealt with the
installer letting you break your hard drive into 'multiple drives,'
probably referred to as C:, E:, F:, and so on.
"You may not realize it, but if you've done this, you've already
created partitions. A partition is a virtual drive inside a drive,
created through storing information about the drive's virtual
layout in special locations on the drive itself. The system's BIOS
and operating system(s) then utilize this information to determine
where to look on the drive for boot instructions and data..."