How does it work? I‘ve looked at countless articles but I do not understand it.
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.
Suppose you want to transfer ink from some surface to the paper or other object. You could make something like a big stamp by carving the surface back until only the bits you want to transfer ink are raised above it, then when you press the stamp into the object it only touches on those raised bits and transfers the ink there. This is called “relief printing”.
The other way of printing is if you scratched or carved a design into the surface and created indentations which ink can be deposited into and then the rest wiped away before the printing plate is pressed into the paper or whatever. This is intaglio printing.