Typography is subordinate to the content; its task is to ensure a pleasant reading experience. Readability can be optimized by a number of subtle details. Each of these details may seem insignificant in itself, but together they form the essence of professional typesetting. Using the advanced typesetting system TeX enables us to apply the highest typographical standards in our books.

Word spacing

One of the most important elements of typography is an even distribution of word space. TeX takes care of this by calculating breaks not per line but rather per paragraph. Moreover, TeX avoids visual incompatibility of adjacent lines, i.e., lines with relatively large spaces will never be followed by lines with small spaces and vice versa.

Character kerning

In a digital font each glyph is preceded and followed by a natural space. In certain combinations of glyphs this space needs adjustment. This process of adjusting the space between glyphs is called character kerning and is necessary to provide an optically even distribution of space between glyphs. For example, between the letter pair ‘A’ and ‘v’ the natural space must be slightly diminished, and between the pair ‘b’ and ‘o’ the space must be slightly increased. Every well-designed font is equipped with a metric file containing hundreds of kerning pairs. TeX’s font mechanism is able to process the kerning data automatically.


In addition to kerning pairs, a metric file also contains ligature data. Ligatures are characters that replace a pair of interfering characters. For example, an ‘f’ followed by an ‘i’ is printed as a single compound character in which the flag of the ‘f’ substitutes the dot on top of the ‘i’. Other common ligatures are ‘fl’, ‘ff’, ‘ffi’ and ‘ffl’. Depending on the design of each particular font, this list is extended with ligatures like ‘fb’, ‘fj’, ‘ct’ and many others.

Italic correction

When italicized text is used within roman text, the space following the italicized text is usually too narrow. Since italicized text inclines to the right, the space after an italicized word seems optically too small. In these cases we add a so-called italic correction after the last character. The width of this adjustment differs per character and is calculated automatically by TeX based on the metric data of a font.

Old-style figures

The use of tabular numbers (numbers with a fixed width and the same character height as capitals) within the running text is considered to be distracting because these numbers disturb the rhythm of the text. In such cases, the use of so-called old-style figures is preferred, as these have ascenders, descenders and a variable width, similar to letters of the alphabet.

Small caps

Similarly, the use of regular capitals in the running text is undesirable, because these are optically too large. We prefer to replace roman numbers and capitalized abbreviations with small capitals (i.e. capitals with the x-height of the font used). With our Automatic Copy Editing system (ACE), we can easily apply these specialized characters in the text.


Many fonts have been designed over the past few centuries. However, only a small number of these fonts is suitable for typesetting books. A book typeface should not draw too much attention and must have a large family: it should not only contain sets of roman and italic characters, but also sets that contain small caps and italic small caps. We like to follow the development of book fonts closely: we keep track of their technological progress (for example, by using the new possibilities offered by Open Type fonts), and we frequently monitor the release of newly designed book typefaces.