Intaglio is a process by which the image is etched or engraved into and below the surface of the plate. The plate is inked, and polished to remove excess, and put through an etching press with dampened paper to pull out the ink from the etched lines and textures below the surface. Etching, engraving, drypoint, aquatint, and mezzotint are intaglio processes.
Relief is a process by which the artist cuts into the surface of the plate, removes chosen sections and then prints from the areas that remain. Linoprint, wood block, wood engraving and letterpress are all relief methods of printmaking. Ink is ususally applied by a roller, the paper is placed over the plate and then passed through a press or burnished by hand to take an impression.
Planographic printing is printing from a flat surface – it includes lithography, which is the process of printing from a stone or metal plate on which the surface is treated to repel ink except where it is required for printing. Stencil printing, such as screenprinting, is also planographic, here ink is forced through a paper, plastic or glue stencil on a fine-meshed cloth screen, normally silk – and so they are sometimes referred to as Silkscreens. Monotypes may also be considered as planographic – it is a process that produces just one unique print. An image is created on a flat surface with a greasy substance such as ink or oil paint. The image is then pressed onto paper or printed on a press.
Caborundum printmaking might be considered to fall outside the above categories – here grit is mixed with a medium and painted onto a plate. Once dry, it is inked and wiped and passed through a press.