Leading

In typography, leading (IPA ) refers to the amount of added space between lines of type. When type was set by hand for printing presses, printers placed slugs—strips of lead of various thicknesses—between lines of type to add space.

Usage

Leading is commonly confused with line height, which refers to the full height of a line of type (the size of the tallest letter in a font of type, plus the thickness of the leading). Text with no leading is set solid. In this case, the line height is equal to the type size.

It is generally considered that text set solid appears a little cramped, with ascenders touching descenders from the previous line. A leading of 20% of the font height (or a line height of 1.2h) is quite common for "normal" text; most Web browsers have a default line height of 1.2h. Desktop publishing packages tend to vary between 10–30% leading.