points out, a comprehensive answer to this would likely be a chapter
in a systems administration manual, so I'll try just to sketch the
basic concepts. Ask new questions if you need more detail on specific
In UNIX, all files in the system are organized into a single
directory tree structure (as opposed to Windows, where you have a
separate directory tree for each drive).
There is a "root" directory, which is denoted by
corresponds to the top directory on the main drive/partition (in the
Windows world, this would be
C:). Any other directory and file in
the system can be reached from the root, by walking down
How can you make other drives/partitions visible to the system in such
a unique tree structure? You mount them: mounting a drive/partition
on a directory (e.g.,
/media/usb) means that the top directory on
that drive/partition becomes visible as the directory being mounted.
Example: if I insert a USB stick in Windows I get a new drive, e.g.,
F:; if in Linux I mount it on directory
/media/usb, then the
top directory on the USB stick (what I would see by opening the
drive in Windows) will be visible in Linux as directory
In this case, the
/media/usb directory is called a "mount point".
Now, drives/partitions/etc. are traditionally called "(block) devices"
in the UNIX world, so you always speak of mounting a device on a
directory. By abuse of language, you can just say "mount this device"
or "unmount that directory".
I think I've only covered your point 1., but this could get you
started for more specific questions.
Check this for further reading.