Lithography is a way of printing from a flat surface, traditionally a slab of limestone. The artist draws on it with a greasy crayon.
Before each print, the stone is wet down and an inked roller passes over it. The ink sticks only to the drawing, because grease and water do not mix, and the paper picks up the image with the grain of the crayon still in it.

The name joins two Greek words, lithos, "stone," and graphein, "to write." Older prints came from lines carved into wood or cut into metal. On a lithographic stone nothing is carved, and the drawing holds on the flat surface by chemistry alone.
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That chemistry was found in the 1790s by Alois Senefelder, a Munich playwright, in Bavaria, in southern Germany. He could not afford to have his plays engraved on copper, so he looked for something cheaper and turned to limestone.
The usual version stops there, with a man who noticed that grease and water do not mix. His own account, a printers' manual published in 1818, is longer. It shows that his first useful print was not flat at all.
Senefelder's laundry list

It began with a household laundry list…
What You'll Discover
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How Goya worked a stone like a canvas.
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