Non-breaking space: Difference between revisions

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In computer-based text processing and digital typesetting, a non-breaking space or no-break space (NBSP) is a variant of the space character that prevents an automatic line break (line wrap) at its position. In certain formats (such as HTML) it also prevents the "collapsing" of multiple consecutive whitespace characters into a single space. The non-breaking space is also known as a hard space or fixed space.

Text-processing software typically assumes that an automatic line break may be inserted anywhere a space character occurs; a non-breaking space prevents this happening (provided the software recognises the character, of course). 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". To avoid this undesirable behaviour, the editor 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 that treat sequences of whitespace characters (space, newline, tab, form feed, etc.) as if they were a single whitespace character. 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.

In contrast, non-breaking spaces are not merged with neighboring whitespace characters, and can therefore be used by an author to insert additional visible space in the formatted text. For example, in HTML, non-breaking spaces may be used in conjunction with a fixed-width font to create tabular alignment:

   Column 1  Column 2
   --------  --------
        1.2       2.3

(notice that the use of the pre tag is an alternative, if not better way to achieve the same result)

If ordinary spaces are used instead then the spaces are collapsed when the HTML is rendered and the layout is broken:

Column 1 Column 2
-------- --------
1.2 2.3

Unicode defines several other non-break space characters that differ from the regular space in width:

• No-break thin space, known in Unicode as "NARROW NO-BREAK SPACE" (U+202F). This is required for French punctuation (before ?, ! or ;).
• Word joiner, encoded in Unicode 3.2 and above as U+2060. The word-joiner does not normally produce any space but prohibits a line break on either side of it.
• The Byte Order Mark, U+FEFF, officially named "ZERO WIDTH NO-BREAK SPACE", can also be used with the same meaning as the word joiner, but in current documents this use is deprecated. See also Zero-width non-breaking space.

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 the SFS setting, the non-breaking space can be entered with the key combination AltGr + Space.^[1]

Typically, authors of keyboard drivers and application programs (e.g., word processors) have devised their own keyboard shortcuts for the non-breaking space. For example:

• Space (punctuation), symbol "Word Joiner"
• Byte order mark, formerly known as "zero width no-break space"
• Punctuation
• Hyphens in computing, for information about hard and non-breaking hyphens
• List of XML and HTML character entity references
• Sentence spacing: The Digital Age