Typesetting is the composition of text by means of arranging physical types or the digital equivalents. Stored letters and other symbols (called sorts in mechanical systems and glyphs in digital systems) are retrieved and ordered according to a language's orthography for visual display. Typesetting requires the prior process of designing a font (also called a typeface).
During much of the letterpress era, movable type was composed by hand for each page. Cast metal sorts were composited into words and lines of text and tightly bound together to make up a page image called a form, with all letter faces exactly the same height to form an even surface of type.
The time and effort required to manually compose the text led to several efforts in the 19th century to produce mechanical typesetting. While some, such as the Page compositor, met with limited success, by the end of the 19th century, several methods had been devised whereby an operator working a keyboard or other devices could produce the desired text.
Computers excel at automatically typesetting and correcting documents. Character-by-character, computer-aided phototypesetting was, in turn, rapidly rendered obsolete in the 1980s by fully digital systems employing a raster image processor to render an entire page to a single high-resolution digital image, now known as image setting.
EPUB (short for electronic publication) is a free and open e-book standard by the International Digital Publishing Forum (IDPF). Files have the extension .epub.
EPUB is designed for reflowable content, meaning that an EPUB reader can optimize text for a particular display device. EPUB also supports fixed-layout content. The format is intended as a single format that publishers and conversion houses can use in-house, as well as for distribution and sale. It supersedes the Open eBook standard.
EPUB became an official standard of the IDPF in September 2007, superseding the older Open eBook standard. In August 2009, the IDPF announced that they would begin work on maintenance tasks of the EPUB standard.
Two broad objectives were defined by this working group: "One set of activities governs maintenance of the current EPUB Standards (i.e. OCF, OPF, and OPS), while another set of activities addresses the need to keep the Standards current and up-to-date." The working group expected to be active through 2010, publishing updated standards throughout its lifetime. On April 6, 2010, it was announced that this working group would complete their update in April 2010.
EPUB 3 consists of a set of four specifications:
EPUB 2.0 was approved in October 2007, with a maintenance update (2.0.1) intended to clarify and correct errata in the specifications being approved in September 2010. EPUB version 2.0.1 consists of three specifications: