How does an eraser work?

Erasers work in relatively the same way that soap does.
Let’s look at the tree elements; the paper, the graphite, and the eraser.
The molecules that comprise the paper have lots of ridges and bumps,
microscopically. When you write graphite is worn off the pencil tip, the
graphite molecules interlock with the paper molecules. Then comes the
eraser. The eraser’s molecular surface is something that the graphite
likes to stick to more than paper. As the eraser is rubbed and worn on the
page, most every graphite molecule it touches has a better bond with it
than the paper. The eraser “dust” that is left over is worn off eraser
with graphite stuck to it. If an eraser is wet, the water molecules are
locking into the eraser molecules, preventing the graphite from bonding as
it would otherwise, and smears your text around.

Three – not tree. Sorry.

thank you northstate for that very informative answer, do ink erasers work in a similar manner? what is differs them from a regular eraser?

well uberbatman, you see the erasable ink took over a decade to develop and needed to be pressurized slightly for continuous flow during use. That being said you can now understand how and why it is easily erasable.