Today's pencils are made with graphite, water and clay (which is used as a binder), and pencil lead has been made this way since Nicolas-Jacques Conté invented the mixture in 1795 [source: Ritter].
Erasers eradicate pencil markings by lifting graphite from the paper you've written on. As you write, particles of graphite from your pencil mix with and cling to particles in the fiber of the paper. Modern erasers are almost always made from petroleum-based synthetic rubber compounds, typically polyvinyl chloride (they're no longer made from natural latex rubber, which is an allergen for some people). Because the particles in the polymer that make up an eraser are stickier than paper, those graphite particles get stuck to the eraser instead. Some erasers are stickier than others and absorb graphite particles more easily, which defines a good or a bad quality eraser.
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Reference:http://electronics.howstuffworks.com/everyday-tech/erasers-erase1.htm
