Thin space
In typography, a thin space is a space character that is usually 1⁄5 or 1⁄6 of an em in width. It is used to add a narrow space, such as between nested quotation marks or to separate glyphs that interfere with one another.
In Unicode, thin space is encoded at U+2009 THIN SPACE (HTML  
·  
). Unicode's U+202F NARROW NO-BREAK SPACE (HTML  
) is a non-breaking space with a width similar to that of the thin space.
In LaTeX and Plain TeX, \thinspace
produces a narrow, non-breaking space. Outside math formulas in LaTeX, \,
also produces a narrow, non-breaking space, but inside math formulas it produces a narrow, breakable space.
In Microsoft Word, in the symbol dialog (often available via Insert > Symbol or Insert > Special Characters), both the thin space and the narrow no-break space are available for point-and-click insertion. In Word's Symbol dialog, under font = "(normal text)", they are found in subset = "General Punctuation". Other word processing programs have ways of producing a thin space.