leading - technical definition

Pronounced "ledding." In typography, the vertical spacing between lines of type (between baselines). The name comes from the early hot-metal days of typesetting when the space was achieved with thin bars of lead. Leading is measured in points and includes the point size of the typeface and the actual space between the lines. Thus, 15 points of leading using 12 point type really means three points of space in between lines. See typeface.