Интерлиньяж в типографике: расстояние между строками текста

In typography, spacing between lines

In typography, leading ('/l//ɛ//d//ɪ//ŋ/ LEDing) is the space between adjacent lines of type; the exact definition varies. In hand typesetting, leading is the thin strips of lead (or aluminium) that were inserted between lines of type in the composing stick to increase the vertical distance between them. The thickness of the strip is called leading and is equal to the difference between the size of the type and the distance from one baseline to the next. For instance, given a type size of 10 points and a distance between baselines of 12 points, the leading would be 2 points. The term is still used in modern page layout software such as QuarkXPress, the Affinity Suite, and Adobe InDesign. Consumer oriented word processing software often talks of line spacing or, more accurately, interline spacing.

The word comes from lead strips that were put between set lines of lead type, hence the pronunciation "ledding" and not "leeding". The practice became popular in the eighteenth century.

Leading can be used to enhance the legibility of a page or block of text. The standard leading used in printing is usually +2 points for mechanically set body text, or +20% in digital typesetting. In both cases, with a 10 pt font the usual leading is 12 pt, creating a 10/12 ratio, which is considered single spacing. Some type designers recommend a leading between 20% and 45% of the font size. Double spacing is an entrenched practice due to the era of typewriters and, in academic settings, to allow the addition of handwritten comments and proofreading. Typewriters had a limited number of options for leading, and double spacing was chosen as a default. Double spacing increases the amount of unused white space on a page and reduces the number of lines on a page. Too much leading can cause continuity problems, as the eyes of the reader are required to travel a greater distance between lines of text. 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, makes rivers more obvious, and hampers readability.

Leading can be affected by a series of issues, all of which can be rectified or used to the printer's advantage. Negative leading applies only to digital type. An example of negative leading is (12/10) where 2 points are removed from the default leading. A negative leading could be viewed as a hindrance to readability. It would cause the text to be harder to read, as lines would be forced together, lessening room between lines and hindering readability. However, for short bursts of text a negative leading can enhance the message of the text and can create a more effective text.

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.

In metal typesetting some fonts have default increased or decreased leading. To achieve this, a smaller font face is cast on the body of a larger font or vice versa. Such fonts are usually called "bastard" fonts or types. The usual way of indicating such a font is to write the face size first, then a slash and the body size: 10/12 means a 10 point face on a 12 point body, and 12/10 means a 12 point face on a 10 point body.