XKCD Explained
Number 1015
Date Feb. 10th 2012
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Kerning is the 1015th xkcd comic.


Kerning is the art and science of spacing letters and punctuation ("glyphs" in typographical terms) so text is both maximally legible and attractive.

Before linotype and phototypesetting, text was kerned by sliding movable type in a composing stick, later binding it into a "forme" for printing a page. Control over kerning was limited.

In phototypesetting, type was composed by exposing a photosensitive material (typically creating black text on white paper, or clear text on black film). Each letter-pair for a given typeface had a specific kerning value that allowed adjacent letters to be placed a particular distance apart.

For "Display Type" - large ad copy, signs and other prominent uses of large type, phototypeset type was frequently kerned by hand. Type on paper was covered on the reverse side with adhesive wax, the text was cut up with an Xacto knife, and a designer or layout artist re-assembled the type on a "board" by hand, with visual attention to the look of the glyphs. This reassembly often happened during creation of "a mechanical".

When computers began to be able to kern type onscreen, lack of knowledge about kerning meant kerned type had a rough transition into digital representation. Kerning was frequently awful - but went unnoticed by programmers and engineers who didn't recognize the issue in play. Designers, meanwhile, gritted their teeth and used the systems as best they could.

This is the meaning of the XCKD joke: Once you learn to kern type, you can't NOT see bad kerning everywhere - and it shows up EVERYWHERE because not everyone who can now set type, can kern type well, or even knows that it's done.

Kerning Examples: "H" and "I" can be placed very close to each other: "HI", but need enough space to be discernable as separate glyphs. "Y" and "A" can be placed so closely that the imaginary rectangles that surround each glyph actually overlap: "YA".

In "monospaced" fonts (typically used in command-lines, terminals and programming environments), each letter takes up exactly the same horizontal space, and letters are not variably kerned.

In XKCD cartoon #1015, the type on the sign that says "CITY OFFICES" is kerned badly in at least two places. For people who are sensitive to kerning, the sign looks like (exaggeration added for demonstration): "C ITY OFFIC  ES".

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"I have never been as self-conscious about my handwriting as when I was inking in the caption for this comic."

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