Lithography is the only one among the four major graphic techniques of which the origin and indeed the invention are documented. Moreover, the process reached a high state of development very soon after its invention, for within a few years a range of variations had been explored, including transfer methods, direct drawing on stone, and engraving on stone. The word "lithography" is derived from the Greek and means "stone writing." As compared to relief (with its raised printing surface), and intaglio (with its depressed surface), lithography is a flat-surface or planographic printing method, depending upon the antipathy of grease and water. The principles of lithography were accidentally discovered and then perfected in Munich in the 1790's by a young actor-playwright, Alois Senefelder(1771-1834).

In essence, the process that Senefeler eventually perfected consisted of several steps. He would write or draw with greasy crayon directly on the stone. The stone was then treated with nitric acid and water, after which gum arabic was applied. Senefelder found that after he dampened the stone, the ink adhered to the design and not to the pat of the stone that had absorbed water. He could then pull an impression on paper against the stone.

Some of the most innovative work in printmaking being done today is in the realm of lithography. Many artists, for example, are experimenting with commercial offset lithography methods.

The offset press can print lithographs form zinc or aluminum plates wrapped around a cylinder. As the plate is dampened and inked, the impressions are then offset onto another cylinder covered with a smooth composition rubber blanket. This impression is then transferred to the paper under pressure.

Taken from: Printmaking: History and Process, Donal Saff and Deli Sacilotto