The width of a space varies among different fonts and renderers. In electronic documents, most renderers introduce line breaks (wrap the line) at the last breaking space when a line of text exceeds the available display width, and will expand all normal spaces to justify columns of text. The non-breaking space, ] [, is an alternative to the usual space that can be entered to prevent a line of text from wrapping at its position, and may be used for example between a digit and a unit of measurement, such as 60 km/hr. The non-breaking space will not expand in justified text, and is the preferred white-space character to carry combining diacritics that do not have spacing variants in the font, such as with U+0311 to create / ̑/ as the long falling toneme in Serbo-Croatian.
In traditional metal type, the width of an 'em space' is the type size in points, whereas an 'en space' is half that. Thus, in 12-point text, an em space is 12 points wide, an en space 6 points, a three-per-em ('thick') space 4 points, a four-per-em ('mid') space 3 points, a six-per-em space 2 points, and a hairline space less than that. These conventions largely carry over into electronic documents, though whereas a 'thin space' is nominally five-per-em, in computer typography it may be conflated with six-per-em.
The figure space is used to align columns of numbers. It's the tabular width of the font, that is, the width of a digit in typefaces that have fixed-width digits.
A punctuation space is the width of narrow punctuation such as a full stop, and is used for example to separate the thousands in strings of digits.
Unicode defines a medium mathematical space as four-eighteenths of an em.
From the vaporwave subculture which uses full-width lettering to write words. This style produces what appears to be spaces between each letter, leading to vaporwave-related terms being spelled with spaces between each letter to replicate this style (for example, the spacing in "ｖａｐｏｒｗａｖｅ", in full-width, is replicated using spaces as "v a p o r w a v e").[1]
(typography)A narrow non-breaking space, used to space out the punctuation marks ?, !, « », :, ;, %, ‹ ›, € and other currency symbols, and between opening and closing –
In traditional French typography, the non-breaking space should be a narrow one, called a espace fine insécable in French; however, due to technological restraints, a normal non-breaking space is used in its place. Nonetheless, in everyday French, a normal space is often used instead.
In standard Quebec orthography, the non-breaking space should only be used before :, between « », before %, before currency symbols, and between opening and closing –.[1]
^ Office québécois de la langue française ((Can we date this quote?)), “Espacement avant et après les principaux signes de ponctuation et autres signes ou symboles”, in Banque de dépannage linguistique[1] (in French)
space (punctuation) on Wikipedia.Wikipedia 