In typography, leading ( LED-ing) identifies the distance between your baselines of successive lines of type. The word originated in the times of hand-typesetting, when skinny strips of business lead were inserted in to the forms to raise the vertical distance between lines of type. The word is still found in modern page-layout software such as QuarkXPress and Adobe InDesign.
In consumer-oriented word-processing software, this idea is usually known as “line spacing” or “interline spacing”.

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