How does an external hard drive work?
Think of an external hard drive like a normal hard drive working
outside your computer, they work very much in the same way.
Normally (unless you are using a SCSI, PATA, or eSATA hard drive),
they can be connected to your computer via a Firewire or USB
connection. If you have a key-drive (aka USB memory stick), they
work like a miniature external hard drive in the sense that they
store date in an external format; an external hard drive is just
like a large key-drive. With both a key-drive and an external hard
drive, you simply connect it to your computer, and access its
files. When you want to access your internal hard drive, you go to
My Computer and then select the C: drive; The external hard drive
is a similar process, you select it's icon (located either on the
desktop or My Computer) and then you can access its files like a
normal hard drive. You can drag files out of it onto your desktop,
or alternatively, drag files into it to transfer files from your
computer.