Hi Nancy, It is an optical mouse and while I can't really give a technical explanation it looks just like any other mouse from the top. But it has a little red light in the bottom. That red light is a optical device that senses as you move the mouse across the mouse pad and then moves the cursor on the screen. No little ball to clean. I just wipe off the mouse ever once in a while. The information that came with mine indicated that you didn't even need a mouse pad. Just move it across your table or desk surface. Am setting here right now with 2 computers side by side. Both have an optical mouse. I have a mouse pad with one and use the other one with a mouse pad. Can't really tell the difference at all in terms of having or not having a mouse pad. Both work great. Hope this helps a bit. Take care - Emma In a message dated 8/12/2005 10:13:30 PM Central Standard Time, mamat@gvtel.com writes: Emma, How does it work, if it doesn't have a ball? And this one isn't all that old, maybe 2-3 years...(of course, my definition of "old", may not be the same as what the "mouse" thinks~!!) Thanks, NancyT