 = Sentence spacing = 
 
 Sentence spacing is the horizontal space between sentences in typeset text . It is a matter of typographical convention . Since the introduction of movable @-@ type printing in Europe , various sentence spacing conventions have been used in languages with a Latin alphabet . 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 method — some printers used spacing between sentences that was no wider than word spacing . This was French spacing — a term synonymous with single @-@ space sentence spacing until the late 20th century . 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 . While wide sentence spacing was phased out in the printing industry in the mid @-@ twentieth century , the practice continued on typewriters and later on computers . Perhaps because of this , many modern sources now incorrectly claim that wide spacing was created for the typewriter . 
 The desired or correct sentence spacing is often debated but many sources now say additional space is not necessary or desirable . From around 1950 , single sentence spacing became standard in books , magazines and newspapers 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 . The debate continues on the World Wide Web . Many people prefer double sentence spacing for informal use because that was how they were taught to type . There is a debate on which convention is more readable ; the few recent direct studies conducted since 2002 have produced inconclusive results . 
 
 = = History = = 
 
 
 = = = Traditional typesetting = = = 
 
 Shortly after the invention of movable type , highly variable spacing was created that could create spaces of any size , and allowed for perfectly even justification . 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 guides — e.g. , Jacobi in the UK ( 1890 ) and MacKellar , Harpel , and De Vinne ( 1866 – 1901 ) in the U.S. — indicated that sentences should be em @-@ spaced , and that words should be 1 / 3 or 1 / 2 em @-@ spaced ( illustration right ) . The relative size of the sentence spacing would vary depending on the size of the word spaces and the justification needs . For most countries , this remained the standard for published work until the 20th century . Yet , even in this period , there were publishing houses ( notably in France ) that used a standard word space between sentences — a technique called French spacing ( illustration below ) . 
 
 = = = 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 . 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 spacing — typists 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 sentences to approximate the wider sentence spacing used in traditional printing , but later settled on two spaces , a practice that continued throughout the 20th century . This became known as English spacing , and marked a divergence from French typists , who continued to use French spacing . 
 
 = = = 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 . This standard continued in use , to some extent , into the 1990s . 
 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 . Typists did not move to single spacing simultaneously . The average writer still relied on the typewriter to create text — with its inherent mechanical spacing limitations . 
 Technological advances began affecting sentence spacing methods . In 1941 , IBM introduced the Executive , a typewriter capable of proportional spacing — 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 . By the 1960s , electronic phototypesetting systems ignored runs of white space in text . This was also true of the World Wide Web , as HTML normally ignores additional spacing , 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 . By the late 20th century , literature on the written word had begun to adjust its guidance on sentence spacing . 
 
 = = Modern literature = = 
 
 
 = = = Typography = = = 
 
 Early positions on typography ( the " arrangement and appearance of text " ) 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 . 
 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 . 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 . 
 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 the single space is " standard typographic practice " . 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 : 
 Word spaces , preceding or following punctuation , should be optically adjusted to appear to be of the same value as a standard word space . If a standard word space is inserted after a full point or a comma , then , optically , this produces a space of up to 50 % wider than that of other word spaces within a line of type . This is because these punctuation marks carry space above them , which , when added to the adjacent standard word spaces , combines to create a visually larger space . Some argue that the " additional " space after a comma and full point serves as a " pause signal " for the reader . But this is unnecessary ( and visually disruptive ) since the pause signal is provided by the punctuation mark itself . 
 
 = = = Style and language guides = = = 
 
 
 = = = = Style guides = = = = 
 
 Early style guides for typesetting used a wider space between sentences than between words – " traditional spacing " , as shown in the illustration to the right . During the 20th century , style guides commonly mandated two spaces between sentences for typewritten manuscripts , which were used prior to professionally typesetting the work . As computer desktop publishing became commonplace , typewritten manuscripts became less relevant and most style guides stopped making distinctions between manuscripts and final typeset products . In the same period , style guides began changing their guidance on sentence spacing . The 1969 edition of the Chicago Manual of Style used em spaces between sentences in its text ; by the 2003 edition it had changed to single sentence spacing for both manuscript and print . By the 1980s , the United Kingdom 's Hart 's Rules ( 1983 ) had shifted to single sentence spacing . Other style guides followed suit in the 1990s . Soon after the beginning of the 21st century , the majority of style guides had changed to indicate that only one word space was proper between sentences . 
 Modern style guides provide standards and guidance for the written language . These works are important to writers since " virtually all professional editors work closely with one of them in editing a manuscript for publication . " Late editions of comprehensive style guides , such as the Oxford Style Manual ( 2003 ) in the United Kingdom and the Chicago Manual of Style ( 2010 ) in the United States , provide standards for a wide variety of writing and design topics , including sentence spacing . The majority of style guides now prescribe the use of a single space after terminal punctuation in final written works and publications . A few style guides allow double sentence spacing for draft work , and the Gregg Reference Manual makes room for double and single sentence spacing based on author preferences . Web design guides do not usually provide guidance on this topic , as " HTML refuses to recognize double spaces altogether . " These works themselves follow the current publication standard of single sentence spacing . 
 The European Union 's Interinstitutional Style Guide ( 2008 ) indicates that single sentence spacing is to be used in all European Union publications — encompassing 23 languages . For the English language , the European Commission 's English Style Guide ( 2010 ) states that sentences are always single @-@ spaced . The Style Manual : For Authors , Editors and Printers ( 2007 ) , first published in 1966 by the Commonwealth Government Printing Office of Australia , stipulates that only one space is used after " sentence @-@ closing punctuation " and that " Programs for word processing and desktop publishing offer more sophisticated , variable spacing , so this practice of double spacing is now avoided because it can create distracting gaps on a page . " 
 National languages not covered by an authoritative language academy typically have multiple style guides — only some of which may discuss sentence spacing . This is the case in the United Kingdom . The Oxford Style Manual ( 2003 ) and the Modern Humanities Research Association 's MHRA Style Guide ( 2002 ) state that only single spacing should be used . In Canada , both the English and French language sections of the Canadian Style , A Guide to Writing and Editing ( 1997 ) , prescribe single sentence spacing . In the United States , many style guides — such as the Chicago Manual of Style ( 2003 ) — allow only single sentence spacing . The most important style guide in Italy , Il Nuovo Manuale di Stile ( 2009 ) , does not address sentence spacing , but the Guida di Stile Italiano ( 2010 ) , the official guide for Microsoft translation , tells users to use single sentence spacing " instead of the double spacing used in the United States " . 
 
 = = = = Language guides = = = = 
 
 Some languages , such as French and Spanish , have academies that set language rules . Their publications typically address orthography and grammar as opposed to matters of typography . Style guides are less relevant for such languages , as their academies set prescriptive rules . For example , the Académie française publishes the Dictionnaire de l 'Académie française for French speakers worldwide . The 1992 edition does not provide guidance on sentence spacing , but is single @-@ sentence @-@ spaced throughout — consistent with historical French spacing . The Spanish language is similar . The most important body within the Association of Spanish Language Academies , the Real Academia Española , publishes the Diccionario de la Lengua Española , which is viewed as prescriptive for the Spanish language worldwide . The 2001 edition does not provide sentence spacing guidance , but is itself single sentence spaced . The German language manual Empfehlungen des Rats für Deutsche Rechtschreibung ( " Recommendations of the Council for German Orthography " ) ( 2006 ) does not address sentence spacing . The manual itself uses one space after terminal punctuation . Additionally , the Duden , the German language dictionary most commonly used in Germany , indicates that double sentence spacing is an error . 
 
 = = = Grammar guides = = = 
 
 A few reference grammars address sentence spacing , as increased spacing between words is punctuation in itself . Most do not . Grammar guides typically cover terminal punctuation and the proper construction of sentences — but not the spacing between sentences . Moreover , many modern grammar guides are designed for quick reference and refer users to comprehensive style guides for additional matters of writing style . For example , the Pocket Idiot 's Guide to Grammar and Punctuation ( 2005 ) points users to style guides such as the MLA Style Manual for consistency in formatting work and for all other " editorial concerns " . The Grammar Bible ( 2004 ) states that " The modern system of English punctuation is by no means simple . A book that covers all the bases would need to be of considerable breadth and weight and anyone interested in such a resource is advised to consult the Chicago Manual of Style . " 
 
 = = Digital age = = 
 
 In the computer era , spacing between sentences is handled in several different ways by various software packages . Some systems accept whatever the user types , while others attempt to alter the spacing , or use the user input as a method of detecting sentences . Computer @-@ based word processors , and typesetting software such as troff and TeX , allow users to arrange text in a manner previously only available to professional typesetters . 
 The text editing environment in Emacs uses a double space following a period to identify the end of sentences unambiguously ; the double space convention prevents confusion with periods within sentences that signify abbreviations . How Emacs recognizes the end of a sentence is controlled by the settings sentence @-@ end @-@ double @-@ space and sentence @-@ end . The vi editor also follows this convention ; thus , it is relatively easy to manipulate ( jump over , copy , delete ) whole sentences in both emacs and vi . 
 The Unix typesetter program troff uses two spaces to mark the end of a sentence . This allows the typesetter to distinguish sentence endings from abbreviations and to typeset them differently . Early versions of troff , which only typeset in fixed width fonts , would automatically add a second space between sentences , which were detected based on the combination of terminal punctuation and a line feed . 
 Microsoft Word does not treat sentences differently by default , but the grammar checking can be set to prefer a specific number of spaces between sentences . 
 On some modern touch @-@ screen platforms , including Android and iOS , typing two spaces in a row is automatically interpreted to mean the end of a sentence , and a period is automatically inserted . However , only one space is retained . 
 Multiple spaces are eliminated by default in most World Wide Web content , regardless of whether they are associated with sentences or not . There are options for preserving spacing , such as the CSS white @-@ space property , and the < pre > tag . Twitter retains extra spaces in user input on their website . HTML also includes several other space entities which are not collapsed , such as an em space , an en space , and a non @-@ breaking space . Some unicode space characters are also not collapsed on the web . 
 
 = = Controversy = = 
 
 James Felici , author of the Complete Manual of Typography , says that the topic of sentence spacing is " the debate that refuses to die ... In all my years of writing about type , it 's still the question I hear most often , and a search of the web will find threads galore on the subject " . This subject is still widely debated today . 
 Many people are opposed to single sentence spacing for various reasons . Some state that the habit of double spacing is too deeply ingrained to change . Others claim that additional space between sentences improves the aesthetics or readability of text . Proponents of double sentence spacing also state that some publishers may still require double @-@ spaced manuscript submissions from authors . A key example noted is the screenwriting industry 's monospaced standard for screenplay manuscripts , Courier , 12 @-@ point font , although some works on screenwriting indicate that Courier is merely preferred – proportional fonts may be used . Some reliable sources state simply that writers should follow their particular style guide , but proponents of double spacing caution that publishers ' guidance takes precedence , including those that ask for double sentence spaced manuscripts . 
 One of the most popular arguments against wider sentence spacing is that it was created for monospaced fonts of the typewriter , and is no longer needed with modern proportional fonts . However , proportional fonts existed together with wide sentence spacing for centuries before the typewriter , and remained for decades after its invention . When the typewriter was first introduced , typists were most commonly taught to use three spaces between sentences . This gradually shifted to two spaces , while the print industry remained unchanged in its wide em @-@ spaced sentences . Some sources now state it is acceptable for monospaced fonts to be single spaced today , although other references continue to specify double spacing for monospaced fonts . The double space typewriter convention has been taught in schools in typing classes , and that remains the practice in many cases . Some voice concerns that students will later be forced to relearn how to type . 
 Most style guides indicate that single sentence spacing is proper for final or published work today , and most publishers require manuscripts to be submitted as they will appear in publication — single sentence spaced . Writing sources typically recommend that prospective authors remove extra spaces before submitting manuscripts , although other sources state that publishers will use software to remove the spaces before final publication . 
 
 = = Effects on readability and legibility = = 
 
 Claims abound regarding the legibility and readability of the single and double sentence spacing methods — by proponents on both sides . Supporters of single spacing assert that familiarity with the current standard in books , magazines , and the Web enhances readability , that double spacing looks strange in text using proportional fonts , and that the " rivers " and " holes " caused by double spacing impair readability . Proponents of double sentence spacing state that the extra space between sentences enhances readability by providing clearer breaks between sentences and making text appear more legible , particularly noting the very small visual difference between a dot and a comma . 
 However , typographic opinions are typically anecdotal with no basis in evidence . " Opinions are not always safe guides to legibility of print " , and when direct studies are conducted , anecdotal opinions — even those of experts — can turn out to be false . Text that seems legible ( visually pleasing at first glance ) may be shown to actually impair reading effectiveness when subjected to scientific study . 
 
 = = = Studies = = = 
 
 Direct studies on sentence spacing include those by Loh , Branch , Shewanown , and Ali ( 2002 ) ; Clinton , Branch , Holschuh , and Shewanown ( 2003 ) ; and Ni , Branch , and Chen ( 2004 ) , with results favoring neither single , double , nor triple spacing . The 2002 study tested participants ' reading speed for single and double sentence spaced passages of on @-@ screen text . The authors stated that " the ' double space group ' consistently took longer time to finish than the ' single space ' group " but concluded that " there was not enough evidence to suggest that a significant difference exists . " The 2003 and 2004 studies analyzed on @-@ screen single , double , and triple spacing . In both cases , the authors stated that there was insufficient evidence to draw a conclusion . Ni , Branch , Chen , and Clinton conducted a similar study in 2009 using identical spacing variables . The authors concluded that the " results provided insufficient evidence that time and comprehension differ significantly among different conditions of spacing between sentences " . 
 
 