The following items have each been considered part of prepress at one time or another: typesetting, copyediting, markup, proofreading, page layout, screening (of continuous-tone images such as photographs), retouching, page assembly (stripping), imposition (combination of many pages into a single signature form), trapping (also referred to as spreading and choking), separation (specifying images or text to be put on plates applying individual printing mediums [inks, varnishes, etc.] to a common print) and platemaking (photomechanical exposure and processing of light-sensitive emulsion on a printing plate).
However, in most modern environments the tasks relating to content generation and refinement are carried out separately from other prepress tasks, and are commonly characterized as being part of a different process (i.e.: graphic design). Some companies combine the role of graphic design and prepress production in a role or job title known as desktop publisher or DTP associate.
The set of procedures used in any particular prepress environment is known as a workflow. Workflows vary, depending on the printing process (e.g., letterpress, offset, digital printing, screen printing), on the final product (books, newspapers, product packaging), and on the implementation of specific prepress technologies. For example, it is not uncommon to use a computer and imagesetter to generate film which is then stripped and used to expose the plate in a vacuum frame; this workflow is hybrid because separation and halftoning are carried out via digital processes while the exposure of the plate is carried out via an analog one.
During the 1980s and 1990s, computer-aided prepress techniques began to supplant the traditional dark room and light table processes, and by the early 2000s the word prepress became, in some ways, synonymous with digital prepress. Immediately before the mainstream introduction of computers to the process, much of the industry was using large format cameras to make emulsion-based (film) copies of text and images. This film was then assembled (stripping) and used to expose another layer of emulsion on a plate, thus copying images from one emulsion to another. This method is still used; however, as digital prepress technology has become less costly, more efficient and reliable, and as the knowledge and skill required to use the new hardware and especially software have become more widespread within the labor force, digital automation has been introduced to almost every part of the process. Some topics related to digital but not analog prepress include preflighting (verifying the presence, quality and format of each digital component), color management, and RIPping.
PDF workflows also became predominant. Vendors of Prepress systems embraced the PDF format, and submitted a subset of PDF as a standard to ANSI and OSI called PDF/X (PDF for eXchange).