From The Art of the Printmaker handout:
"The art of printmaking designates basically the ability to reproduce repeatedly an image or design from a master image. Early printmaking was generally religious and communicational in purpose. As more advanced communications developed, the hand printing processes attracted artists by the richness and variety. Soon, the public, collectors and others placed value on high-quality prints at artists used printmaking processes more creatively.
Limiting the edition size of the print, and numbering and signing each print identifies the quantity and quality of the work. The earlier the impression the sharper and the more valuable the print. While there may be the financial temptation to print large editions, the value of each individual print decreases as size of the edition increases.
Evolution in the technical processes of printmaking have confused many collectors and jurors. For example, there are three-dimensional prints as well as prints which don't use ink or paint at all. Today the quality of an individual print is frequently determined by an artist's mastery of his individual technique. However, in some instances each work must be evaluated without preconception of technique or other constraints. Aesthetic and/or technical considerations do not always solely determine a work's quality.
Main categories of printmaking are:
Relief prints, resulting from a raised printed surface, e.g. wood cut.
Intaglio printing, the image areas are depressed below the surface instead of raised. These techniques include engraving, etching, dry point, mezzotint and aquatint.
Lithography is a planographic process, which means that the printed surface is flat - printing is dependent on chemical reactions.
Stencil process in which ink or color is applied to the perforated or cut out sections of specially treated paper, e.g. serigraph or silkscreen prints.
Allied processes include monotype, plaster-mold prints, photomechanical processes, photography, collotype and holograms.
In spite of the variety of printing today, printmakers have one common pleasure - that of pulling a high-quality print off a well-defined plate - stone or block."