In the beginning, the rules of the space bar were simple. Two spaces after each period. Every time. Easy.
But then, at the end of the 20th century, the typewriter gave way to the word processor, and the computer, and modern variable-width fonts. And the world divided.
Some insisted on keeping the two-space rule. They couldn't get used to seeing just one space after a period. It simply looked wrong.
Some said this was blasphemy. The designers of modern fonts had built the perfect amount of spacing, they said.
And when you really get right down to it, aren't we being pretty closed-minded to accept the false dichotomy of "one space" versus "two space", when here in this bright future we have such a glorious manifold panoply of spacing possibilities?
- SPACE -- ' ' -- sometimes considered a control code
- NO-BREAK SPACE -- ' ' -- commonly abbreviated as NBSP
- ETHIOPIC WORDSPACE -- '፡'
- OGHAM SPACE MARK -- ' ' -- glyph is blank in "stemless" style fonts
- EN QUAD -- ' '
- EM QUAD -- ' ' -- mutton quad
- EN SPACE -- ' ' -- nut; half an em
- EM SPACE -- ' ' -- mutton; nominally, a space equal to the type size in points;may scale by the condensation factor of a font
- THREE-PER-EM SPACE -- ' ' -- thick space
- FOUR-PER-EM SPACE -- ' ' -- mid space
- SIX-PER-EM SPACE -- ' ' -- in computer typography sometimes equated to thin space
- FIGURE SPACE -- ' ' -- space equal to tabular width of a font; this is equivalent to the digit width of fonts with fixed-width digits
- PUNCTUATION SPACE -- ' ' -- space equal to narrow punctuation of a font
- THIN SPACE -- ' ' -- a fifth of an em (or sometimes a sixth)
- HAIR SPACE -- ' ' -- thinner than a thin space; in traditional typography, the thinnest space available
- ZERO WIDTH SPACE -- '' -- commonly abbreviated ZWSP; this character is intended for invisible word separation and for line break control; it has no width, but its presence between two characters does not prevent increased letter spacing in justification
- NARROW NO-BREAK SPACE -- ' ' -- commonly abbreviated NNBSP; a narrow form of a no-break space, typically the width of a thin space or a mid space
- MEDIUM MATHEMATICAL SPACE -- ' ' -- abbreviated MMSP; four-eighteenths of an em
- SYMBOL FOR SPACE -- '␠'
- BLANK SYMBOL -- '␢' -- graphic for space
- OPEN BOX -- '␣' -- graphic for space
- IDEOGRAPHIC SPACE -- ' '
- IDEOGRAPHIC HALF FILL SPACE -- '〿' -- visual indicator of a screen space for half of an ideograph
- ZERO WIDTH NO-BREAK SPACE -- '' -- BOM, ZWNBSP; may be used to detect byte order by contrast with the noncharacter code point U+FFFE; use as an indication of non-breaking is deprecated; see WORD JOINER instead
- TAG SPACE -- ''
I always type two spaces, though HTML hides that. It's what they taught me when I was pressing my Cuneiform reeds into the clay, and the habit was reinforced by the justification idiosyncrasy that M-j fill-paragraph-or-region does not break lines at a single space following a period so that mid-sentence abbreviations are never wrapped from the following word. Which is another thing that HTML hides.
But then, for decades I used to type double-quotes ``like this'' in English text because ASCII doesn't contain ““” and “””. I eventually gave up on that, but by that time I had developed such an abiding hatred of "smart" quotes that now I just use straight-up-and-down ASCII double quotes for everything.
Also, punctuation goes inside the quotation marks only if the punctuation is part of the thing being quoted, because that's proper scoping, and I'll die on that hill.