Sentence spacing concerns how spaces are inserted between sentences in typeset text and is a matter of typographical convention.University of Chicago Press 2003, Chicago Manual of Style. p. 243; Einsohn 2006. p. 113; Shushan and Wright 1989. p. 34. Since the introduction of movable-type printing in Europe, various sentence spacing conventions have been used in languages with a Latin alphabet.Languages with Sanscrit, Cyrillic, cuneiform, hieroglyphics, Chinese, and Japanese characters, among others, are not covered in the scope of this article. Handwriting is also not covered. These include a normal word space (as between the words in a sentence), a single enlarged space, and two full spaces.
Until the 20th century, publishing houses and printers in many countries used additional space between sentences. There were exceptions to this traditional spacing methodsome printers used spacing between sentences that was no wider than word spacing. This was French spacing, synonymous with single-space sentence spacing until the late 20th century.In the 1990s some print and Web sources began referring to double sentence spacing as "French spacing", leading to some ambiguity with the term. See for example, Eckersley et al. 1994. p. 46, and Haley 2006. With the introduction of the typewriter in the late 19th century, typists used two spaces between sentences to mimic the style used by traditional typesetters.Bringhurst 2004. p. 28. While wide sentence spacing was phased out in the printing industry in the mid-20th century, the practice continued on typewritersFelici 2003. p. 80. and later on computers.Jury 2009. p. 58. Perhaps because of this, many modern sources now incorrectlyFelici 2009. claim that wide spacing was created for the typewriter.Jury 2009. p. 57; Williams 2003. p. 13; Fogarty 2008. p. 85.
The desired or correct sentence spacing is often debated, but most sources now state that an additional space is not necessary or desirable.Felici 2003. p. 80; Fogarty 2008. p. 85; Jury 2009. p. 56; Strizver 2010; Walsh 2004. p. 3; Williams 2003. pp. 13–14. From around 1950, single sentence spacing became standard in books, magazines, and newspapers,Williams 2003. pp. 13–14. This refers to professionally published works, as it is possible for individual authors to publish works through desktop publishing systems. Williams states, "I guarantee this: never in your life have you read professionally set text printed since 1942 that used two spaces after each period." See also, Felici 2003, p. 81; Strizver 2010; Weiderkehr 2009; Williams 1995. p. 4. and the majority of style guides that use a Latin-derived alphabet as a language base now prescribe or recommend the use of a single space after the concluding punctuation of a sentence.; However, some sources still state that additional spacing is correct or acceptable. Some people prefer double sentence spacing because that was how they were taught to type.Strizver 2010. The few direct studies conducted since 2002 have produced inconclusive results as to which convention is more readable.Lloyd and Hallahan 2009. "During times when many disciplines that recommend the APA's Publication Manual [6th ed., 2009] are advocating evidence-based decisions, it's noteworthy, we think, that these discussions of the rationale for using two spaces at the end of sentences (and after colons) do not appear to be based on scientific examination of the hypothesis that two spaces makes manuscripts more readable."
History
Traditional typesetting
Shortly after the invention of movable type, highly variable spacing was created, which could create spaces of any size and allowed for perfectly even justification.DeVinne 1901. p. 142. Early American, English, and other European typesetters' style guides (also known as printers' rules) specified spacing standards that were all essentially identical from the 18th century onwards. These guidese.g., Jacobi in the U.K. (1890)Jacobi 1890. and MacKellar, Harpel, and De Vinne (1866–1901) in the U.S.MacKellar 1885; Harpel 1870. p. 19; DeVinne 1901. p. 78.indicated that sentences should be em-spaced, and that words should be 1/3 or 1/2 em-spaced. The relative size of the sentence spacing would vary depending on the size of the word spaces and the justification needs.Chicago University Press 1911. p. 101. Variable-spaced text (professionally typeset) is unlikely to result in a sentence space exactly twice the size of a word space (which can be seen with a typewriter or monospaced font). Variables such as whether a 1/3 or 1/2-word space is used, and whether the text is justified or unjustified, will vary the difference between a sentence space and word space. For most countries, this remained the standard for published work until the 20th century.Felici 2009. Felici illustrates that there are other examples of standard single word spaces used for sentence spacing in this period. Yet, even in this period, there were publishing houses that used a standard word space between sentences.
Mechanical type and the advent of the typewriter Mechanical type systems introduced near the end of the 19th century, such as the Linotype and Monotype machines, allowed for some variable sentence spacing similar to hand composition.Dodd 2006. p. 73; Mergenthaler Linotype 1940. Just as these machines revolutionized the mass production of text, the advent of the typewriter around the same time revolutionized the creation of personal and business documents. But the typewriters' mechanical limitations did not allow variable spacingtypists could only choose the number of times they pressed the space bar. Typists in some English-speaking countries initially learned to insert three spaces between sentencesOne or two spaces after a period? How about three? to approximate the wider sentence spacing used in traditional printing, but later settled on two spaces,Jury 2009. p. 58. This refers primarily to the United States and Great Britain. a practice which continued throughout the 20th century. This became known as "English spacing" and marked a divergence from French typists, who continued to use French spacing.Imprimerie nationale 1993.
Transition to single spacing In the early 20th century some printers began using one-and-a-half interword spaces (an "en quad") to separate sentences.Osgood 1919. This standard continued in use, to some extent, into the 1990s.Adams, et al. 1996. p. 24. Adams, Faux, and Rieber say, "For most composition, the em quad is used to indent the first line of a paragraph, the en quad is used to separate sentences, and the 3em space is placed between words." An en is half an em and a 3em space is a third of an em, so the space between sentences would be 1.5 times the space between words.
Magazines, newspapers, and books began to adopt the single-space convention in the United States in the 1940s and in the United Kingdom in the 1950s.Felici 2009; University of Chicago Press 2009; Williams 2003. p. 14. Typists did not move to single spacing simultaneously.
Technological advances began affecting sentence spacing methods. In 1941 IBM introduced the Executive, a typewriter capable of proportional spacing,Wershler-Henry 2005. pp. 254–255. which had been used in professional typesetting for hundreds of years. This innovation broke the hold that the monospaced font had on the typewriter, reducing the severity of its mechanical limitations. However, this innovation did not spread throughout the typewriter industry; the majority of mechanical typewriters, including all the widely distributed models, remained monospaced, while a small minority of special models carried the innovations. By the 1960s electronic phototypesetting systems ignored runs of white space in text. This was also true for the World Wide Web, as HTML normally ignores additional spacing,Lupton 2004. p. 165. HTML normally ignores all additional horizontal spacing between text. although in 2011 the CSS 2.1 standard officially added an option that can preserve additional spaces. In the 1980s desktop publishing software provided the average writer with more advanced formatting tools.Jury 2009. p. 57.
Modern literature Typography Early positions on typography (the "arrangement and appearance of text")American Medical Association 2007. p. 917. supported traditional spacing techniques in English publications. In 1954 Geoffrey Dowding's book Finer Points in the Spacing and Arrangement of Type underscored the widespread shift from a single enlarged em space to a standard word space between sentences.Dowding 1995.
With the advent of the computer age, typographers began deprecating double spacing, even in monospaced text. In 1989 Desktop Publishing by Design stated that "typesetting requires only one space after periods, question marks, exclamation points, and colons" and identified single sentence spacing as a typographic convention.Shushan and Wright 1989. p. 34. Stop Stealing Sheep & Find Out How Type Works (1993) and Designing with Type: The Essential Guide to Typography (2006) both indicate that uniform spacing should be used between words, including between sentences.Craig 2006. p. 90; Spiekermann and Ginger 1993, p. 123.
More recent works on typography weigh in strongly. Ilene Strizver, founder of the Type Studio, says: "Forget about tolerating differences of opinion: typographically speaking, typing two spaces before the start of a new sentence is absolutely, unequivocally wrong." The Complete Manual on Typography (2003) states that "The typewriter tradition of separating sentences with two-word spaces after a period has no place in typesetting" and that the single space is "standard typographic practice".Felici 2003. pp. 80–81. The Elements of Typographic Style (2004) advocates a single space between sentences, noting that "your typing as well as your typesetting will benefit from unlearning this quaint [double spacing] Victorian habit".
David Jury's book About Face: Reviving the Rules of Typography (2004, published in Switzerland) clarifies the contemporary typographic position on sentence spacing:Jury 2004. p. 92.
Style and language guides
Style guides