Welcome to he wonderful world of abrasives. There are many different kinds of abrasives so pay close attention and hopefully you learn something that you don't already know.
Some of you already know about sandpaper but did you know that the abrasives category includes sheets, disks, drums, pads, and belts? Those are only in the paper category.
Other types of abrasives include anything that is sued to remove material. Some examples include powders like pumice, and other things like steel wool and polishing cloths.