Boldface

In typography, emphasis is the exaggeration of words in a text with a font in a different style from the rest of the text—to emphasize them. It is the equivalent of prosodic stress in speech.

The most common methods in Bold fall under the general technique of emphasis through a change or modification of font: italics, boldface and small caps. Other methods include the alteration of letter case and spacing as well as color and additional graphic marks.

The human eye is very receptive to differences in "brightness within a text body". Therefore, one can differentiate between types of emphasis according to whether the emphasis changes the “blackness” of text. A means of emphasis that does not have much effect on “blackness” is the use of italics, where the text is written in a script style, or the use of oblique, where the vertical orientation of all letters is slanted to the left or right. With one or the other of these techniques (usually only one is available for any typeface), words can be highlighted without making them stand out much from the rest of the text (inconspicuous stressing). This was used for marking passages that have a different context, such as words from foreign languages, book titles, and the like.

By contrast, a bold font weight makes text darker than the surrounding text. With this technique, the emphasized text strongly stands out from the rest; it should therefore be used to highlight certain keywords that are important to the subject of the text, for easy visual scanning of text. For example, printed dictionaries often use boldface for their keywords, and the names of entries can conventionally be marked in bold. If the publisher prefers not to use bold, or has already used it for another purpose, a second form of emphasis can be introduced by using a lightface or thin version of the main text font, although this is not very common.

Small capitals are also used for emphasis, especially for the first line of a section, sometimes accompanied by or instead of a drop cap, or for personal names as in bibliographies.

If the text body is typeset in a serif typeface, it is also possible to highlight words by setting them in a sans serif face. This practice is often considered archaic in Latin script, and on computers is complicated since fonts are no longer issued by foundries with a standard baseline, so switching font may distort linespacing. It is still possible using some font superfamilies, which come with matching serif and sans-serif variants, though these are not generally supplied with modern computers as system fonts. In Japanese typography, due to the reduced legibility of heavier Minchō type, the practice remains common.

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