==== Spaces ====

  * 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 -- '󠀠'

(via https://www.metafilter.com/173964/We-are-obliged-not-to-tolerate-their-wanton-and-conscious-blasphemy#7393199 )