Improvement is the process of a thing moving from one state to a state considered to be better, usually through some action intended to bring about that better state. The concept of improvement is important to governments and businesses, as well as to individuals.
In typography, leading ( LED-ing) refers to the distance between the baselines of successive lines of type. The term originated in the days of hand-typesetting, when thin strips of lead were inserted into the forms to increase the vertical distance between lines of type. The term is still used in modern page-layout software such as QuarkXPress and Adobe InDesign.