In word processing and digital typesetting, a non-breaking space ( ), also called NBSP, required space,^[1] hard space, or fixed space (in most typefaces, it is not of fixed width), is a space character that prevents an automatic line break at its position. In some formats, including HTML, it also prevents consecutive whitespace characters from collapsing into a single space. Non-breaking space characters with other widths also exist.

Despite having layout and uses similar to those of whitespace, it differs in contextual behavior.^[2][3]

Text-processing software typically assumes that an automatic line break may be inserted anywhere a space character occurs; a non-breaking space prevents this from happening (provided the software recognizes the character). For example, if the text "100 km" will not quite fit at the end of a line, the software may insert a line break between "100" and "km". An editor who finds this behavior undesirable may choose to use a non-breaking space between "100" and "km". This guarantees that the text "100 km" will not be broken: if it does not fit at the end of a line, it is moved in its entirety to the next line.

A second common application of non-breaking spaces is in plain text file formats such as SGML, HTML, TeX and LaTeX, whose rendering engines are programmed to treat sequences of whitespace characters (space, newline, tab, form feed, etc.) as if they were a single character (but this behavior can be overridden). Such "collapsing" of whitespace allows the author to neatly arrange the source text using line breaks, indentation and other forms of spacing without affecting the final typeset result.^[4][5]

In contrast, non-breaking spaces are not merged with neighboring whitespace characters when displayed. They can, therefore, be used by an author to simply insert additional visible space in the resulting output without using spans styled with peculiar values of the CSS "white-space" property. Conversely, indiscriminate use (see the recommended use^{[citation needed]} in style guides), in addition to a normal space, gives extraneous space in the output.

Other non-breaking variants, defined in Unicode:

U+202F   NARROW NO-BREAK SPACE (NNBSP)

Due to the tighter binding of value and unit as a continuous visual element NNBSP is recommended for usage in the SI-standard.^[6] It was introduced in Unicode 3.0 for [[Mongolian language|Mongolian],^[7] to separate a suffix^[8] from the word stem without indicating a word boundary. It is also required for big punctuation (sometimes inaccurately referred to as "double punctuation") in French where it is called espace fine insécable (before ;, ?, !, », › and after «, ‹; today often (i.e. in French DTP, referred to^[9] as new-school) also before :) and in German between multi-part abbreviations (e.g., "z. B.", "d. h.", "v. l. n. r.").^[10] When used with Mongolian, its width is usually one third of the normal space; in other contexts, its width is about 70% of the normal space but may resemble that of the thin space (U+2009), at least with some fonts.^[11] Also, starting from release 34 of Unicode Common Locale Data Repository (CLDR), the NNBSP is used in numbers as a group separator in French,^[12] and starting from release 44,^[13] in Venetian.^[14] Spanish is prone to do the same.^[15]

U+2007   FIGURE SPACE ( )

Produces a space equal to the figure (0–9) characters.

U+2060 WORD JOINER (⁠ · WJ)

Encoded in Unicode since version 3.2. The word joiner does not produce any space and prohibits a line break at its position.

On browsers, resizing the window will demonstrate the effect of non-breaking spaces on the texts below.

To show the non-breaking effect of the non-breaking space, the following words have been separated with non-breaking spaces:

Lorem Ipsum Dolor Sit Amet Consectetur Adipiscing Elit Sed Do Eiusmod Tempor Incididunt Ut Labore Et Dolore Magna Aliqua Ut Enim Ad Minim Veniam Quis Nostrud Exercitation Ullamco Laboris Nisi Ut Aliquip Ex Ea Commodo Consequat Duis Aute

To show the non-collapsing behavior of the non-breaking space, the following words have been separated with an increasing number of non-breaking spaces:

Lorem Ipsum  Dolor   Sit    Amet     Consectetur      Adipiscing       Elit        Sed         Do          Eiusmod           Tempor            Incididunt             Ut              Labore               Et                Dolore                 Magna                  Aliqua                   Ut                    Enim                     Ad                      Minim

In contrast, the following words are separated with ordinary spaces: ^{[On a fairly large device, this gives output identical to the first example. Why not just use a longer string of words?]}

Lorem Ipsum Dolor Sit Amet Consectetur Adipiscing Elit Sed Do Eiusmod Tempor Incididunt Ut Labore Et Dolore Magna Aliqua Ut Enim Ad Minim Veniam Quis Nostrud Exercitation Ullamco Laboris Nisi Ut Aliquip Ex Ea Commodo Consequat Duis Aute

Here, they are separated with narrow non-breaking spaces, to show the width of those:

Lorem Ipsum Dolor Sit Amet Consectetur Adipiscing Elit Sed Do Eiusmod Tempor Incididunt Ut Labore Et Dolore Magna Aliqua Ut Enim Ad Minim Veniam Quis Nostrud Exercitation Ullamco Laboris Nisi Ut Aliquip Ex Ea Commodo Consequat Duis Aute

In Unicode, the byte order mark (BOM), U+FEFF, may be interpreted as a "zero width no-break space", but is a deprecated alternative to word joiner (U+2060).

It is rare for national or international standards on keyboard layouts to define an input method for the non-breaking space. An exception is the Finnish multilingual keyboard, accepted as the national standard SFS 5966 in 2008. According to SFS 5966, the non-breaking space can be entered with the key combination AltGr + Space.^[16]

Typically, authors of keyboard drivers and application programs (e.g., word processors) have devised their own keyboard shortcuts for the non-breaking space. (For other entry methods, see Unicode input.)

• Hyphens in computing, for information about hard and non-breaking hyphens
• List of XML and HTML character entity references
• Non-breaking hyphen – Punctuation mark used to join words
• Punctuation – Marks to indicate pacing of written text
• Sentence spacing in digital media – Horizontal width of inter-sentence space
• Space (punctuation) – Blank area that separates text
  • Space (punctuation) § Non-breaking space, for applications
  • Zero-width space – Special character in text processing, a non-spacing break
• Widows and orphans – In typography, an isolated line of text starting/ending a page
• Non-printing character in word processors – Formatting marks for content design
• Typographic alignment § Justified