Underlining

Underlining is the practice of drawing a horizontal line beneath the baseline of text. It is used to emphasize words or phrases, or to indicate items for annotation, editing, or formatting. In handwriting and manuscript traditions, underlines may serve to stress a term or to denote titles when italics were not used or available. In printed typography, underlining has historically functioned as a substitute for italics or for emphasis, especially before italic type became common.

Variants include single, double, dotted, or wavy lines. The line is typically placed directly under the characters; some scripts and fonts require adjustment to avoid collision with descenders or diacritics.

In modern typography and digital contexts, underlining is often reserved for hyperlinks, particularly in web design, where underlined text signals a link. For emphasis, designers increasingly rely on italics or bold rather than underlining. CSS provides text-decoration: underline and related properties such as text-underline-offset and text-decoration-thickness to control appearance.

Accessibility and readability considerations are important: because underlined text is commonly interpreted as a link by screen readers, underlines should not be used on ordinary text meant to be non-link emphasis. When used, the underline should be clearly distinguishable from the surrounding text, and spacing should avoid interfering with line height.

Overall, underlining remains a recognizable tool in handwriting, proofreading, and certain typographic traditions, but its use in modern digital typography is typically domain- and context-specific rather than a general emphasis method.