its like a program that you donload that does random things
i had one on my computer for a bit that lil monkey that you download to your desktop that just sits there and does random things the entire time its running, and you can click on something and it brings up a lil like *do this* icon and you can tell it what to do but the entire time its on your desktop, or when you open like say, internet explorer, itl on the screen but in like the bottom cornor still being used