Letterpress and gravure are two other printing methods that can be offset. When printing halftones, the output device is normally a PostScript laser printer or imagesetter. Resolution varies between 300 dpi and 3300 dpi. This is a big factor in determining screen frequency. If the paper is porous, dot gain will obviate any detail that could be gained from using a high screen frequency.
Papers come in a large variety of types and are intended for many different purposes.
Newsprint A coarser paper made mostly from wood pulp and highly porous. It is manufactured almost exclusively for printing newspapers. Any number of different paper types that are unvarnished. Coated Paper Paper that has been given a varnish coat. High quality grayscale and four-color images are printed on coated stock.