Leading (typography)

"Line spacing is the vertical distance between lines of text," and "the traditional term for line spacing is leading (rhymes with bedding), so named because traditional print shops put strips of lead between lines of type to increase vertical space." The measure is relative to type size: "for most text, the optimal line spacing is between 120% and 145% of the point size," its own samples calling 110% "too tight" and 170% "too loose." It also moves pages more than type size does: "line spacing affects the length of a document more than point size," so it is the first setting to adjust when fitting text to a page count.

That is its job on a fixed print page such as the A6 bunko page: leading is locked with the type size and trim size when the interior is built in how to create a print-ready PDF, whose line-spacing citation this term reuses. Its line-level neighbor is the widow.