UNIX for Dummies Questions & Answers

i'm confused as to what this option does exactly... I see it all the time
in examples...

in my unix text is says the following which is entirely cryptic to me...

tar
f- Specifices the archivefile or tape device. The default tape device is
/dev/rmt/0. If archivefile is "-", then the tar command reads from
standard input or writes to standard output, whichever is appropriate

jar
f - Specifies the jar file or tape drive. The jar command sends the data
to the screen if the "f" option is not used.

can someone explain this to me? from what I gather you have to use the f
option to tell it that the following filename or location is where you
want to store (or is it copy) the archived file? now what happens if you
don't specify a location for either command?

I have never used jar, but in tar the "f" option will will tell it where to write the outgoing data to if creating an archive, or will tell tar where the input file is coming from when reading / extracting an archive.
The argument can be either a raw device (like a tape drive) or a file (like "backup.tar).

In tar, it will try to read from / write to /dev/rmt/0 (depending on what Unix you use, it may be different) if no "f" is supplied.