In writing, a space ( ) is a blank area devoid of content, serving to separate words, letters, numbers, and punctuation. Conventions for interword and intersentence spaces vary among languages, and in some cases the spacing rules are quite complex.
In the classical period, Latin was written with interpuncts (centred dots) as word separators, but that practice was abandoned sometime around AD 200 in favour of scriptio continua, i.e., with the words running together without any word separators. In around AD 600–800, blank spaces started being inserted between words in Latin, and that practice carried over to all languages using the Latin alphabet (e.g. English). In typesetting, spaces have historically been of multiple lengths with particular space-lengths being used for specific typographic purposes, such as separating words or separating sentences or separating punctuation from words. Following the invention of the typewriter and the subsequent overlap of designer style-preferences and computer-technology limitations, much of this reader-centric variation was lost in normal use.
In computer representation of text, spaces of various sizes, styles, or language characteristics (different space characters) are indicated with unique code points.
Modern English uses a space to separate words, but not all languages follow this practice. Spaces were not used to separate words in Latin until roughly AD 600–800. Ancient Hebrew and Arabic did use spaces, partly to compensate in clarity for the lack of vowels.citation needed Traditionally, all CJK languages have no spaces: modern Chinese and Japanese (except when written with little or no kanji) still do not, but modern Korean uses spaces.
Languages with a Latin-derived alphabet have used multiple methods of sentence spacing since the advent of movable type in the 15th century.
- One space (French Spacing). This is the current convention in countries that use the ISO basic Latin alphabet for published and final written work, as well as digital (World Wide Web) media.1
- Double space (English Spacing). This convention stems from the use of the monospaced font on typewriters.2 This historical convention was carried on by tradition until it was replaced by the single space convention in published print and digital media today.345678910111213
- One widened space, typically one-and-a-third to slightly less than two times as wide as a word space. This spacing has been seen in early typesetting practices (prior to the nineteenth century). It has also been used in other non-typewriter typesetting systems such as the Linotype machine14 and the TeX system.15 Modern computer-based digital fonts can adjust the spacing after terminal punctuation as well, creating a space slightly wider than a standard word space.16
- No space. According to Lynne Truss, "young people" today using digital media "are now accustomed to following a full stop with a lower-case letter and no space".17
There has been some controversy regarding the proper amount of sentence spacing in typeset material. The Elements of Typographic Style states that only a single word space is required for sentence spacing since "Larger spaces...are themselves punctuation."18
The International System of Units, or SI,19 and the style guide on the English-language Wikipedia20 recommend a (non-breakable, thin) space between a number and its units, as well as between units in the case of compound units, but never between the prefix of an SI unit and the unit.
- 5.0 cm not 5.0 c m
- 45 kg not 45kg or 45 k g
- 32 °C not 32°C or 32° C
- 20 kN m not 20 kNm or 20 k Nm
- 50% not 50 %
The only exceptions to this rule in the SI are for the symbols for degree, minute and second for plane angle, as 30° 22′ 8″.
For the sake of clarity, a hyphen may be inserted between a numeral and a symbol used adjectivally:
- 35-mm film
- 60-W bulb
However, some other style guides, including Wikipedia's, deprecate hyphenation in these cases. The SI allows a hyphen between the numeral and the unit only when the name of the unit is spelled out, as 35-millimetre film.19
In computer character encodings, there is a normal general-purpose space (Unicode character U+0020; 32 decimal) whose width will vary according to the design of the typeface. Typical values range from 1/5-em to 1/3-em (in digital typography an em is equal to the nominal size of the font, so for a 10-point font the space will probably be between 2 and 3.3 points). Sophisticated fonts may have differently sized spaces for bold, italic, and small-caps faces, and often compositors will manually adjust the width of the space depending on the size and prominence of the text.
In addition to this general-purpose space, it is possible to encode a space of a specific width. See the table below for a complete list.
In monospaced proofreading copy, only em- and en-spaces are represented using this character (which is called an em-quad or an en-quad), while other types of spaces are represented with a number sign (see Number sign#Space in particular).
By default, computer programs usually assume that, in flowing text, a line break may as necessary be inserted at the position of a space. The non-breaking space, U+00A0 (160 decimal), is intended to render the same as a normal space but prevents line-wrapping at that position.
However, there are programs which do not follow this intent exactly, for example even such a modern and widespread web browser like the Mozilla Firefox 3.5 series, released in 2009. It (correctly) suppresses the line-wrapping when rendering the non-breaking space, but it (incorrectly) ignores the
word-spacing CSS property for non-breaking spaces. This was corrected in Firefox version 3.6, released in 2010. Other programs may also suffer from the same flaw. The following simple HTML code demonstrates this flaw on affected browsers:
<html><body style="word-spacing:1em"> <p>This paragraph shows extremely wide spaces between words,<br> because of the 1em word-spacing CSS value.</p> <p>This paragraph contains non-breaking spaces and <br> should show the same spaces as the first one.</p> </body></html>
Here are the above two paragraphs rendered in your current browser:
This paragraph shows extremely wide spaces between words,
because of the 1em word-spacing CSS value.
This paragraph contains non-breaking spaces and
should show the same spaces as the first one.
In American typography, both en dashes and em dashes are set continuous with the text (as illustrated by use in The Chicago Manual of Style, 6.80, 6.83–86). However, an em dash can optionally be surrounded with a so-called hair space, U+200A (8202 decimal), or thin space, U+2009 (8201 decimal). The thin space can be written in HTML by using the named entity
and the hair space can be written using numeric character reference
. This space should be much thinner than a normal space, and is seldom used on its own.
|Normal space||left right|
|Normal space with em dash||left — right|
|Thin space with em dash||left — right|
|Hair space with em dash||left — right|
|No space with em dash||left—right|
Unicode defines21 several space characters with specific semantics and rendering characteristics, as shown in the table below. Depending on the browser and fonts used to view this table, not all spaces may display properly:
|Normal space, same as ASCII character 0x20|
||No-Break Space||Latin-1 Supplement|
|Identical to U+0020, but not a point at which a line may be broken|
|U+1680||5760||Yes||Yes||Ogham Space Mark||Ogham|
|Used for interword separation in Ogham text. Normally a vertical line in vertical text or a horizontal line in horizontal text, but may also be a blank space in "stemless" fonts. Requires an Ogham font.|
|U+180E||6158||Yes||Yes||Mongolian Vowel Separator (MVS)||Mongolian|||
|A narrow space character (not to be confused with "thin space", below) used in Mongolian to cause the final two characters of a word to take on different shapes.22|
|U+2000||8192||Yes||Noa||En quad||General Punctuation|
|Width of one en. U+2002 is canonically equivalent to this character; U+2002 is preferred.|
|Width of one em. U+2003 is canonically equivalent to this character; U+2003 is preferred.|
|Width of one en. U+2000 En Quad is canonically equivalent to this character; U+2002 is preferred.|
|Width of one em. U+2001 Em Quad is canonically equivalent to this character; U+2003 is preferred.|
|One third of an em wide|
|One fourth of an em wide|
|U+2006||8198||Yes||Noa||Six-Per-Em Space||General Punctuation|
|One sixth of an em wide. In computer typography sometimes equated to U+2009.|
|U+2007||8199||No||Noa||Figure Space||General Punctuation|
|In fonts with monospaced digits, equal to the width of one digit.|
|U+2008||8200||Yes||Noa||Punctuation Space||General Punctuation|
|As wide as the narrow punctuation in a font, i.e. the advance width of the period or comma.23|
||Thin Space||General Punctuation|
|One fifth (sometimes one sixth) of an em wide. Recommended for use as a thousands separator for measures made with SI units. Unlike U+2002 to U+2008, its width may get adjusted in typesetting.24|
|U+200A||8202||Yes||Noa||Hair Space||General Punctuation|
|Thinner than a thin space|
|U+200B||8203||Yes||Noa||Zero Width Space (ZWSP)||General Punctuation|||
|Used to indicate word boundaries to text processing systems when using scripts that do not use explicit spacing. It is similar to the soft hyphen, with the difference that the latter is used to indicate syllable boundaries, and should display a visible hyphen when the line breaks at it.|
||Zero Width Non Joiner (ZWNJ)||General Punctuation|||
|When placed between two characters that would otherwise be connected, a ZWNJ causes them to be printed in their final and initial forms, respectively.|
||Zero Width Joiner (ZWJ)||General Punctuation|||
|When placed between two characters that would otherwise not be connected, a ZWJ causes them to be printed in their connected forms.|
|U+202F||8239||No||Noa||Narrow No-Break Space||General Punctuation|
|Similar in function to U+00A0 No-Break Space. Introduced in Unicode 3.0 for Mongolian,25 to separate a suffix from the word stem without indicating a word boundary. When used with Mongolian, its width is usually one third of the normal space; in other context, its width resembles that of the Thin Space (U+2009) at least with some fonts. This char is also used in French before ";?!»" chars and after "«".|
|U+205F||8287||Yes||Noa||Medium Mathematical Space (MMSP)||General Punctuation|
|Used in mathematical formulae. Four-eighteenths of an em.26 In mathematical typography, the widths of spaces are usually given in integral multiples of an eighteenth of an em, and 4/18 em may be used in several situations, for example between the a and the + and between the + and the b in the expression a + b.27|
|U+2060||8288||No||Yes||Word Joiner (WJ)||General Punctuation|||
|Identical to U+200B, but not a point at which a line may be broken. Introduced in Unicode 3.2 to replace the deprecated "zero width no-break space" function of the U+FEFF character.|
|U+3000||12288||Yes||Noa||Ideographic Space (used for example as tai tou)||CJK Symbols and Punctuation|
|As wide as a CJK character cell (fullwidth)|
|U+FEFF||65279||No||Yes||Zero Width No-Break Space
= Byte Order Mark (BOM)
|Arabic Presentation Forms-B|||
|Used primarily as a Byte Order Mark. Use as an indication of non-breaking is deprecated as of Unicode 3.2, see U+2060 instead.|
Unicode also provides some visible characters to stand in for space when necessary:
|U+00B7||183||Middle dot||Basic Latin||·||interpunct, used in text processors. HTML also:
|U+237D||9085||Shouldered open box||Miscellaneous Technical||⍽||used for NBSP|
|U+2420||9248||Symbol for space||Control Pictures||␠|
|U+2422||9250||Blank symbol||Control Pictures||␢|
|U+2423||9251||Open box||Control Pictures||␣|
In programming language syntax, spaces are frequently used to explicitly separate tokens. Aside from this use, spaces and other whitespace characters are usually ignored by modern programming languages. Exceptions are Haskell, occam, ABC, and Python, which use the amount of whitespace in indentation to indicate the bounds of a block, and a whimsical language called Whitespace, where whitespace is the only meaningful syntactical element.
In commands processed by command processors, e.g. in scripts and typed in, the space character can cause problems as it has two possible functions: as part of a command or parameter, or as a parameter or name separator. Ambiguity can be prevented either by prohibiting embedded spaces, or by enclosing a name with embedded spaces between quote characters.
Text editors, word processors, and desktop publishing software differ in how they represent whitespace on the screen, and how they represent spaces at the ends of lines longer than the screen or column width. In some cases, spaces are shown simply as blank space; in other cases they may be represented by an interpunct or other symbols. Many different characters (described below) could be used to produce spaces, and non-character functions (such as margins and tab settings) can also affect whitespace.
Hard spaces (contrasted with "soft spaces") may be defined by some word processors and operating systems as either a non-breaking space, a non-combining/non-expanding space, or some other special character.
Generalised markup languages, such as SGML, do not treat space characters differently from other characters.
However, special-purpose markup languages may. In particular, web markup languages such as XML and HTML treat whitespace characters specially, including space characters, for programmers' convenience. One or more space characters read by conforming Display-time processors of those markup languages are collapsed to 0 or 1 space, depending on their semantic context. For example, double (or more) spaces within text are collapsed to a single space, and spaces which appear on either side of the "
=" that separates an attribute name from its value have no effect on the interpretation of the document. Element end tags can contain trailing spaces, and empty-element tags in XML can contain spaces before the "
In XML attribute values, sequences of whitespace characters are treated as a single space when the document is read by a parser.30 Whitespace in XML element content is not changed in this way by the parser, but an application receiving information from the parser may choose to apply similar rules to element content. An XML document author can use the
xml:space="preserve" attribute on an element to instruct the parser to discourage the downstream application from altering whitespace in that element's content.
In most HTML elements, a sequence of whitespace characters is treated as a single inter-word separator, which may manifest as a single space character when rendering text in a language that normally inserts such space between words.31 Conforming HTML renderers are required to apply a more literal treatment of whitespace within a few prescribed elements, such as the
pre tag and any element for which CSS has been used to apply
pre-like whitespace processing. In such elements, space characters will not be "collapsed" into inter-word separators.
In both XML and HTML, the non-breaking space character, along with other non-"standard" spaces, is not treated as collapsible "whitespace", so it is not subject to the rules above.
- Space Between Words: The Origin of Silent Reading, Paul Saenger
- Einsohn, Amy (2006). "Punctuation, Eyeballing every mark". The Copyeditor's Handbook: A Guide for Book Publishing and Corporate Communications (2nd ed.). Berkeley, Los Angeles, London: University of California Press. p. 113. ISBN 9780520246881. Retrieved 2010-04-25. "If you are working on documents that will be printed without any intervention from a compositor (e.g. documents produced on the office laser printer), you will have to carefully scrutinize every piece of punctuation to be sure that the document contains the correct character (see table 5). You should also delete any extra wordspacing before and after punctuation marks. The conventions are: One space follows sentence-ending punctuation mark (period, question mark, or exclamation point). One space follows comma, colon, or semicolon ..."
- Farhad Manjoo (2011-01-13). "Space Invaders: Why you should never, ever use two spaces after a period.". Slate. Retrieved 2011-03-29.
- Felici, James (2003). The Complete Manual of Typography: A Guide to Setting Perfect Type. Berkeley, CA: Peachpit Press. p. 80. ISBN 0321127307.;
- David Spencer (24 May 2011). "The Curious Misconception Surrounding Sentence Spacing". Type Desk. Matador. Retrieved 27 May 2011.
- Bringhurst, Robert (2004). The Elements of Typographic Style (3 ed.). Washington and Vancouver: Hartley & Marks. p. 28. ISBN 0881792063. "2.1.4 Use a single word space between sentences. In the nineteenth century, which was a dark and inflationary age in typography and type design, many compositors were encouraged to stuff extra space between sentences. Generations of twentieth century typists were then taught to do the same, by hitting the spacebar twice after every period [full stop]. Your typing as well as your typesetting will benefit from unlearning this quaint Victorian habit. As a general rule, no more than a single space is required after a period, colon, or any other mark of punctuation"
- Schriver, Karen (1997). Dynamics in Document Design: Creating Text for Readers (1 ed.). New York: Wiley. p. 502. ISBN 9780471306368. "Use one space (not two) after these punctuation marks [sc. period, question mark, exclamation point, or colon], as the practice of using two spaces is just another holdover from using a typewriter."
- Strauss, Jane (2007). "Spacing with Punctuation". The Blue Book of Grammar and Punctuation: An Easy-to-Use Guide with Clear Rules, Real-World Examples, and Reproducible Quizzes (10 ed.). Jossey-Bass. p. 176. ISBN 9780470222683. Retrieved 2010-04-25. "Rule 1. With a computer, use only one space following periods, commas, semicolons, colons, exclamation points, question marks, and quotation marks. The space needed after these punctuation marks is proportioned automatically. With some typewriters and word processors, follow ending punctuation with two spaces when using a fixed-pitch font."
- "2.49 Leading and spacing". The GPO Style Manual (30 ed.). Washington: The U.S. Government Printing Office. 2008. p. 469. ISBN 9780160818127. Retrieved 2010-04-25. "A single justified word space will be used between sentences. This applies to all types of composition."
- "FAQ: How many spaces should I leave after a period or other concluding mark of punctuation?". MLA Handbook for Writers of Research Papers (7 ed.). Modern Language Association. 2009. p. 292. ISBN 978-0-87352-297-7. Retrieved 2010-04-25. "Publications in the United States today usually have the same spacing after a punctuation mark as between words on the same line. Since word processors make available the same fonts used by typesetters for printed works, many writers, influenced by the look of typeset publications, now leave only one space after a concluding punctuation mark. In addition, most publishers' guidelines for preparing electronic manuscripts ask authors to type only the spaces that are to appear in print."
- "FAQ: How many spaces should I leave after a period or other concluding mark of punctuation?". The Chicago Manual of Style (7 ed.). University of Chicago Press. 2009. p. 292. ISBN 9780873522977. Retrieved 2010-04-25. "Publications in the United States today usually have the same spacing after a punctuation mark as between words on the same line. Since word processors make available the same fonts used by typesetters for printed works, many writers, influenced by the look of typeset publications, now leave only one space after a concluding punctuation mark. In addition, most publishers' guidelines for preparing electronic manuscripts ask authors to type only the spaces that are to appear in print."
- "The Chicago Manual of Style Online (Q&A: One Space or Two?)". University of Chicago Press. 2003. Retrieved 2010-04-25. "The view at CMOS is that there is no reason for two spaces after a period in published work. Some people, however—my colleagues included—prefer it, relegating this preference to their personal correspondence and notes. I’ve noticed in old American books printed in the few decades before and after the turn of the twentieth century (ca. 1870–1930 at least) that there seemed to be a trend in publishing to use extra space (sometimes quite a bit of it) after periods. And many people were taught to use that extra space in typing class (I was). But introducing two spaces after the period causes problems: (1) it is inefficient, requiring an extra keystroke for every sentence; (2) even if a program is set to automatically put an extra space after a period, such automation is never foolproof; (3) there is no proof that an extra space actually improves readability—as your comment suggests, it’s probably just a matter of familiarity (Who knows? perhaps it’s actually more efficient to read with less regard for sentences as individual units of thought—many centuries ago, for example in ancient Greece, there were no spaces even between words, and no punctuation); (4) two spaces are harder to control for than one in electronic documents (I find that the earmark of a document that imposes a two-space rule is a smattering of instances of both three spaces and one space after a period, and two spaces in the middle of sentences); and (5) two spaces can cause problems with line breaks in certain programs. So, in our efficient, modern world, I think there is no room for two spaces after a period. In the opinion of this particular copyeditor, this is a good thing."
- "Chapter 5. Manuscript Preparation and Sample Papers to be Submitted for Publication". Publication Manual of the American Psychological Association (aka APA Style) (5 ed.). Washington: American Psychological Association. 2001. p. 439. ISBN 9781557987907. Retrieved 2010-04-25. "5.11 Spacing and Punctuation: Space once after all punctuation as follows: after commas, colons, and semicolons; after punctuation marks at the end of sentences; after periods that separate parts of a reference citation; and after the periods of the initials in personal names (e.g. J. R. Zhang). Exception: Do not use space after internal periods in abbreviations (e.g. a.m, i.e, U.S.)"
- Style Manual: for Authors, Editors and Printers (aka AGPS Style) (6 ed.). Stafford, Australia: Wiley Australia, The Commonwealth Government of Australia Printing Office. 2002. p. 117. ISBN 978-0-7016-3647-0. Retrieved 2010-04-25. "In typewritten (as distinct from typeset) material, it was customary to place two spaces after a colon, semicolon, full stop or other sentence closing punctuation. 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."
- Mergenthaler Linotype Company (1940). Linotype Keyboard Operation: Methods of Study and Procedures for Setting Various Kinds of Composition on the Linotype. Mergenthaler Linotype Company. cited in Mark Simonson (5 March 2004). "Double-spacing after Periods". Typophile. Typophile. Retrieved 5 April 2010.
- Eijkhout, Victor (2008), TeX by Topic, A TeXnician's Reference (pdf), Lulu, pp. 185–188
- Felici, James (2003). The Complete Manual of Typography: A Guide to Setting Perfect Type. Berkeley, CA: Peachpit Press. p. 80. ISBN 0-321-12730-7.; Fogarty, Mignon (2008). Grammar Girl's Quick and Dirty Tips for Better Writing (Quick and Dirty Tips). New York: Holt Paperbacks. p. 85. ISBN 978-0-8050-8831-1.; Straus, Jane (2009). The Blue Book of Grammar and Punctuation: An Easy-to-Use Guide with Clear Rules, Real-World Examples, and Reproducible Quizzes (10th ed.). San Francisco, CA: Jossey-Bass. p. 52. ISBN 978-0-470-22268-3.
- Truss, Lynn (2004). Eats, Shoot & Leaves: The Zero Tolerance Approach to Punctuation. New York: Gotham Books. p. 25. ISBN 1-59240-087-6.
- Bringhurst, Robert (2004). The Elements of Typographic Style (3.0 ed.). Washington and Vancouver: Hartley & Marks. pp. 29–30. ISBN 0-88179-206-3.
- The International System of Units (SI) (8 ed.). International Bureau of Weights and Measures (BIPM). 2006. p. 133..
- "Wikipedia: Manual of Style (dates and numbers)". Section 'Units of measurement': Wikipedia. Retrieved 28 January 2011.
- The Unicode Standard ver. 5.2.0 – section 6.2 table 6-2, and section 16.2 Line and Word Breaking
- Gillam, Richard (2002). Unicode Demystified: A Practical Programmer's Guide to the Encoding Standard. Addison-Wesley. ISBN 0-201-70052-2.
- "Character design standards – space characters". Character design standards. Microsoft. 1998–1999. Retrieved 2009-05-18.
- The Unicode Standard 5.0, printed edition, p.205
- ISO/IEC 10646-1:1993/FDAM 29:1999(E)
- "General Punctuation" (PDF). The Unicode Standard 5.1. Unicode Inc. 1991–2008. Retrieved 2009-05-13.
- Sargent, Murray III (2006-08-29). "Unicode Nearly Plain Text Encoding of Mathematics (Version 2)". Unicode Technical Note #28. Unicode Inc. pp. 19–20. Retrieved 2009-05-19.
- "Network.IDN.blacklist chars". MozillaZine. 2009-02-24. Retrieved 18 September 2010.
- "3.3.3 Attribute-Value Normalization". Extensible Markup Language (XML) 1.0 (Fifth Edition). World Wide Web Consortium.
- "9.1 White space". W3CHTML 4.01 Specification. World Wide Web Consortium.
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