Vertical spacing: linespacing, alignment and justification

Linespacing or Leading /ˈlɛdɪŋ/ refers to the distance between the baselines of successive lines of type.

Alignment or range, is the setting of text flow or image placement relative to a page, column (measure), table cell or tab.

Justification refers to the degree to which the spaces between words, and, to a lesser extent, between glyphs or letters, are stretched or compressed to align both the left and right ends of each line of text.

Linespacing or leading

Leading /ˈlɛdɪŋ/ refers to the distance between the baselines of successive lines of type. The term originated in the days of hand-typesetting, when slugs or strips of lead of appropriate thickness were inserted into the forms to increase the vertical distance between set lines of lead type. This increased legibility.

The term ‘leading’ is still used in modern page layout software such as QuarkXPress and Adobe InDesign. In consumer-oriented word processing software like Microsoft, this is usually referred to as “line spacing” or “interline spacing.”

The aim is to clearly separate ascenders and descenders of subsequent lines. Without adding so much leading that the eye has difficulty moving from one line to the next. The leading may be increased to align the bottom line of text on a page in a process known as feathering, carding, or vertical justification.

Unlike traditional lettersetting, digital typesetting can easily insert leading of any thickness. Auto-leading is conventionally set at 120% of type size or 2pt greater. However the optimum amount of leading for readability depends on the typeface, and particularly the length of ascenders and descenders. Many typefaces will benefit from increasing the leading slightly.

Alignment

Alignment or range, is the setting of text flow or image placement relative to a page, column (measure), table cell or tab. The type alignment setting is sometimes referred to as text alignment, text justification or type justification.

There are four basic typographic alignments:

  • flush left—the text is aligned along the left margin or gutter, also known as left-aligned or ragged right;
  • flush right—the text is aligned along the right margin or gutter, also known as right-aligned or ragged left;
  • centered—text is aligned to neither the left nor right margin; there is an even gap on each side of each line.
  • justified—text is aligned along the left margin, and letter- and word-spacing is adjusted so that the text falls flush with both margins, also known as fully justified or full justification;

Note that alignment does not change the direction in which text is read; however text direction may determine the most commonly used alignment for that script.

Flush left
In English and most European languages where words are read left-to-right, text is usually aligned “flush left”, meaning that the text of a paragraph is aligned on the left-hand side with the right-hand side ragged. This is the default style of text alignment on the World Wide Web for left-to-right text Quotations are often indented.

Flush right
In other languages that read text right-to-left, such as Arabic and Hebrew, text is commonly aligned “flush right”. Additionally, flush-right alignment is used to set off special text in English, such as attributions to authors of quotes printed in books and magazines, and is often used when formatting tables of data.
Justified

Centered text
Text can also be “centered”, or symmetrically aligned along an axis in the middle of a column. This is often used for the title of a work, and for poems and songs. As with flush-right alignment, centered text is often used to present data in tables. Centered text is considered less readable for a body of text made up of multiple lines because the ragged starting edges make it difficult for the reader to track from one line to the next.

Justification

A common type of text alignment in print media is “justification”, where the spaces between words, and, to a lesser extent, between glyphs or letters, are stretched or compressed to align both the left and right ends of each line of text. Lines in which the spaces have been stretched beyond their normal width are called loose lines, while those whose spaces have been compressed are called tight lines.

Some modern typesetting programs offer four justification options:

  • left justify
  • right justify
  • center justify
  • full justify.

These variants specify whether the last line is flushed left, flushed right, centered or fully justified (spread over the whole column width). In programs that do not offer this extra functionality, justify is equal to left justify.

It is customary to treat the last line of a justified paragraph separately by left or right aligning it, depending on the language direction.

People with dyslexia (particularly Scotopic Sensitivity Syndrome) find that justification helps with cognitive understanding. Judicious hyphenation is also reported to be beneficial for dyslexics.

Justification has been the preferred setting of type in many Western languages through the history of movable type. This is due to the classic Western manuscript book page being built of a column or two columns, which is considered to look “best” if it is even-margined on the left and right. The classical Western column did not rigorously justify, but came as close as feasible when the skill of the penman and the character of the manuscript permitted. Historically, both scribal and typesetting traditions took advantage of abbreviations (sigla), ligatures, and swash to help maintain the rhythm and colour of a justified line.

The use of movable type solidified this preference from a technological point of view. It was much easier to handle and make amendations to large amounts of type that had words or syllables at the ends of lines than it was to respace the ends of lines.

Its use has only waned somewhat since the middle of the 20th century through the advocacy of the typographer Jan Tschichold’s book Asymmetric Typography and the freer typographic treatment of the Bauhaus, Dada, and Russian constructivist movements.

Continuous casting typesetting systems such as the Linotype were able to reduce the jaggedness of the right-hand sides of adjacent lines of flush left composition by inserting self-adjusting space bands between words to evenly distribute white space, taking excessive space that would have occurred at the end of the line and redistributing it between words. This feature, known as “ragged right”, was available in traditional dedicated typesetting systems but is absent from most if not all desktop publishing systems. Graphic designers and typesetters using desktop systems adjust word and letter spacing, or “tracking”, on a manual line-by-line basis to achieve the same effect.

Some modern desktop publishing programs, such as Adobe InDesign, evaluate the effects of all the different possible line-break choices on the entire paragraph, to choose the one that creates the least variance from the ideal spacing while justifying the lines (so as to reduce rivers), and gives the least uneven edge when set with a ragged margin.

Justification sometimes leads to typographic anomalies. One example: when justification is used in narrow columns, exceptionally large spaces appear between only two or three words (creating what is called a loose line). A second example occurs when the spaces between words line up approximately above one another in several loose lines, a distracting river of white space may appear. Rivers appear in right-aligned, left-aligned and centered settings too, but are more likely to flow in justified text due to extra word spacing. Since there is no added white space built into a typical full stop (period), other than that above the full stop itself, full stops only marginally contribute to the river effect.

Both of these problems are reduced by the addition of hyphenation. With older typesetting systems and WYSIWYG word processors, this was at one time done manually, where the compositor or author added hyphenation on a case-by-case basis. Currently, most typesetting systems (also called layout programs) and modern word processors hyphenate automatically by using a hyphenation algorithm. Professional typesetting programs almost always provide for the further use of an exception dictionary, in part because no algorithm hyphenates all words correctly, and in part because different publishers will follow different dictionaries. Different publishers may also have different rules about permissible hyphenation. Most publishers follow a basic system such as the Chicago Manual of Style or Oxford style, but will overlay their own “house style,” which further restrict permissible hyphenation.
At one time, common word-processing software adjusted only the spacing between words, which was a source of this problem. Modern word processing packages, and professional publishing software, significantly reduce the rivers effect through adjusting the spacing between characters as well as using more advanced