the.com/spacing
The art of nothing, deliberately placed, so something can finally be read.
means The amount of empty room between elements — letters, lines, paragraphs, objects — used to organize and clarify them.
from From space, via Latin spatium meaning room or distance, fitted with the -ing suffix that turns a thing into the act of doing it; long a term of typesetters who literally slotted metal blanks between letters.
KerningAdjusting space between two specific letter pairs.
Mind the gapTracking spaces all letters uniformly, not pairs.
Brain biasCrowded text reads slower and feels harder.