Non-breaking space

Numbers with units

Text-processing software can divide expressions like "100 km" when they do not quite fit at the end of a line. A non-breaking space between "100" and "km" prevents this, and guarantees that "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. Many style guides recommend that numbers and the associated units not be split across lines; non-breaking spaces are used to ensure this.^[4][5]

Spacing punctuation in French

In French typography, non-breaking spaces are used before "high punctuation" (:, ;, ?, and !), on the interior side of guillemets (« and »), and before footnote references. In the case of ;, ?, !, and footnote references (unless enclosed by parentheses), a narrow non-breaking space is used.^[6][7]

Multi-part abbreviations in German

In German typography, it is used between multi-part abbreviations (e.g., "z. B.", "d. h.", "v. l. n. r.").^[8]

Non-collapsing behavior

Non-breaking spaces are used 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.^[9][10]

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 first few words of this phrase have been separated with many ordinary spaces but are displayed (rendered by the Browser engine) as single spaces:

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim

Non-void or non-missing behavior

In programming languages or in software analysis languages (such as SAS or R) non-breaking spaces can be useful to fill character-type variables with spaces that are not to be considered insignificant. In general, a string filled with spaces can be interpreted as an empty string or a string of missing data. Replacing ordinary spaces with non-breaking spaces helps resolving the ambiguity between "space", "void" and "missing".

Narrow non-breaking space

U+202F   NARROW NO-BREAK SPACE (NNBSP) is a non-breaking space that is narrower than the standard non-breaking space (U+00A0). For Mongolian, its is usually one third the width of a normal space;^[11] 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.^{[citation needed]}

This text replaces spaces with narrow 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

Narrow non-breaking space was introduced in 1999 in Unicode 3.0 for Mongolian,^[12] to separate a suffix from the word stem without indicating a word boundary. It also triggers special shaping of those suffixes.^[13] Starting in Unicode 16.0, it is no longer recommended for this purpose, with the Mongolian vowel separator (U+180E) taking on this function.^[14][15]

In French typography, it is called espace fine insécable^[14] and is used before ;, ?, and ! (with the exception of : before which a regular non-breaking space is used).^[6][7] Additionally, a footnote reference is preceded by a narrow non-breaking space^[7] (unless it is enclosed by parentheses, in which case a regular non-breaking space is used).^[6]

The narrow non-breaking space is used in numbers as a group separator in French (starting in Unicode CLDR 34^[16]) and Venetian (starting in Unicode CLDR 44^[17]). In Spanish, the Royal Spanish Academy and Association of Academies of the Spanish Language's Diccionario panhispánico de dudas prescribes a small space as the number group separator,^[18] although this is not the case in Unicode's Common Locale Data Repository (CLDR).^[19]

Figure space

A figure space is a non-breaking space whose width is equal to the figure (0–9) characters.