What exactly are stop words? I've heard alot about them recently. I know they're something to do with the auto tagging system but what exactly do they do?

Thanks

The are small linking words that crop up all of the time like - I, it, you, they, a etc.

and the auto tagging system on installation will include these in thread tags, although you can choose how often a word needs to be included to qualify as a tag. I've been using 2-3 and these are cropping up in tags, which you don't want.
It is likely that they will crop up as many times as your good key words so I have posted a separate thread asking how to exclude these from the tagging process.

Google stop words