Verb

leading

1. Present participle of lead.

Adjective

leading (comparative more leading, superlative most leading)

Positive leading

Comparative more leading

Superlative most leading

1. Providing guidance or direction.

   Avoiding leading questions if you really want the truth.

2. Ranking first.

   He is a leading supplier of plumbing supplies in the county.

3. Occurring in advance; preceding.

   The stock market can be a leading economic indicator.

Coordinate terms

• (occurring in advance): concurrent, lagging

Derived terms

• leading indicator

In typography, leading (pronounced /ˈlɛdɪŋ/, rhymes with heading) refers to the amount of added vertical spacing between lines of type. In consumer-oriented word processing software, this concept is usually referred to as "line spacing", but in page layout software such as QuarkXPress and Adobe InDesign the term "leading" is still used. Leading may sometimes be confused with tracking, which refers to the horizontal spacing between letters or characters.

The word comes from lead strips that were put between set lines. When type was set by hand in printing presses, slugs or strips of lead (reglets) of appropriate thicknesses were inserted between lines of type to add vertical space, to fill available space on the page.

Text set "solid" (no leading) appears cramped, with ascenders almost touching descenders from the previous line. The lack of white space between lines makes it difficult for the eye to track from one line to the next, and hampers readability.

The following block of text has no leading:

Typography (Greek: typos "form", graphein "to write") is the art and technique of setting written subject matter in type using a combination of typeface styles, point sizes, line lengths, line leading, character spacing, and word spacing to produce typeset artwork in physical or digital form.

This block of text set with 50% leading is easier to read:

Typography (Greek: typos "form", graphein "to write") is the art and technique of setting written subject matter in type using a combination of typeface styles, point sizes, line lengths, line leading, character spacing, and word spacing to produce typeset artwork in physical or digital form.

This block of text at 100% leading is also easy to read, but makes less efficient use of vertical page space:

Typography (Greek: typos "form", graphein "to write") is the art and technique of setting written subject matter in type using a combination of typeface styles, point sizes, line lengths, line leading, character spacing, and word spacing to produce typeset artwork in physical or digital form.

In CSS, leading is implemented by creating a difference between the content height and the value of the line-height property. Half the leading is called the half-leading. User agents center glyphs vertically in an inline box, which adds half-leading on the top and bottom. For example, if a piece of text is '12px' high and the line-height value is '14px', 2pxs of extra space should be added: 1px above and 1px below the letters. (This applies to empty boxes as well, as if the empty box contained an infinitely narrow letter.)