I have found the term "dithering" in a few audio applications that I use (most importantly Adobe Audition and foobar2000). What actually is this and what can it be used for?

In foobar2000 (v0.8.3), I have found it in the "Diskwriter" part, where I have options to dither "never", "always" and "only lossy sources". Does it make any difference, e.g. when I transcode a high-bitrate lossy source to a lower-bitrate file for my portable player, whether I dither or not?
In Audition, when I convert the sample rate/bit depth, I am asked whether I want to dither the audio stream, and I am also asked about some types of dithering (Triangular, Rectalgular, Gaussian, and so on). What do these terms mean and what difference do they make, once used?

I'm sorry if this has already been asked or if I have a completely wrong picture about this. Any help would be appreciated.

The Wikipedia entry for "Dithering" is a good starting point.

I found the part about the origin of the word really curious!

Sergio

OK, this looks fairly interesting. But what exactly does it mean in practice?
I mean, to look back at my foobar2000 diskwriter question - does this mean that dithering while transcoding will actually produce worse results than transcoding without dithering?

Thanks.

Here is an interesting paper on dither in audio: http://www.users.qwest.net/%7Evolt42/caden...erExplained.pdf

Here guru performed a listening test including the effects of dither:
http://www.hydrogenaudio.org/forums/index....showtopic=17728

And here's how it should be used in fb2k and why:
http://www.hydrogenaudio.org/forums/index....showtopic=12716

PS. Here is how I found all this info:

As far as I know, dither is most often used to decrease the chance of artefacts when converting audio to a lower bit depth - not bitrate.

Thanks everyone for the info.

krazy, thanks for dropping the links and reminding me of search - i just got used to avoiding it, bcos i've recently been around a few forums which were giving me quite bad results while searching. this is definitely not the case here.