What is a troll?

Someone help me out here please. I’m very new and utterly ignorant. If someone could explain any other terms I should know I would appreciate their help.

Thanks

The master addressed that here: http://www.straightdope.com/mailbag/mtroll.html

That wasn’t written by the master. If it were, it would have also shown local usage, which is here.
http://boards.straightdope.com/sdmb/showthread.php?threadid=2528&pagenumber=2

Have SDSTAFF David and SDSTAFF Ed been given promotions?

D’oh.