Leading

In typography, leading (pronounced ledd-ing) refers to the amount of added space between lines of type. When type was set by hand for printing presses, printers placed slugs of lead between lines of type to add space. Leading is commonly confused with line height, which refers to the full height of a line of type (the size of the type itself plus the leading). Text with no leading is set solid. In this case, the line height is equal to the type size.