The flat plate it scratched or etched to create channels or divots for ink to settle in.
Then, ink is put on the plate and **the excess wiped off**. That leaves only ink in the divots.
A highly flexible paper, usually moistened is laid on top of the plate and rolled through a press with decent pressure. The paper fibers make contact with the ink left in those scratches and etched areas, and pull it up into the paper.
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