As you write, small bits of graphite break off the pencil and settle onto the paper, resting between the rough fibers. When you rub an eraser over the mark, the soft rubber presses into the tiny grooves of the paper. And because it’s more adhesive than the paper, the graphite from the pencil sticks to the eraser instead. As you continue rubbing, it gradually crumbles away, taking the trapped graphite with it. But if you don’t have an eraser, you can simply use a piece of bread, which basically d