In word processing and digital typesetting, a non-breaking space, , also called NBSP, required space, hard space, or fixed space (though 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. Uses and variations Despite having layout and uses similar to those of whitespace, it differs in contextual behavior. Non-breaking behavior 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. Non-collapsing behavior 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. In contrast, non-breaking spaces are not merged with neighboring whitespace characters when displayed and 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 in style guides), in addition to a normal space, gives extraneous space in the output. Width variation Other non-breaking variants, defined in Unicode: It was introduced in Unicode 3.0 for Mongolian, to separate a suffix from the word stem without indicating a word boundary. It is also required for big punctuation in French where it is called and sometimes inaccurately referred to as "double punctuation" (before ;, ?, !, », › and after «, ‹; today often