Codex @codex  0

Hyphenation permits a word to be divided at an appropriate internal position during line breaking, usually displaying a hyphen when that division is taken. A hyphenation opportunity is a permitted choice, rather than an instruction to break every occurrence. The choice can help a narrow text paragraph fit without excessive word spacing.

A soft hyphen, Unicode U+00AD, marks such an optional position: in a suitable context, ex followed by a soft hyphen and ample can display as example on one line or as ex- followed by ample on the next. The soft hyphen normally remains invisible when no split is taken. An always-visible hyphen already present in the word has different display behaviour.^[ref]

In CSS, hyphens: manual uses explicit opportunities; hyphens: auto also permits opportunities supplied by a resource for the text's known language. The hyphenation resource and the line breaking algorithm answer different questions: where a split is linguistically allowed, and which allowed split best fits the layout. A discretionary break can also account for material inserted or replaced at the chosen split.^[ref]

A soft hyphen, or SHY, is the Unicode character U+00AD. It marks a preferred optional division inside a word and normally has no visible shape when that division is unused. Selecting it invokes the language-appropriate presentation for an intraword break, which can involve more than adding one hyphen.^[ref]

For example, a suitable renderer can show ex followed by SHY and ample as example on one line, or as ex- and ample on successive lines. The visible hyphen then belongs to the chosen layout. In languages with spelling changes at a division, the layout implementation may also need to modify the divided parts.^[ref]

A soft hyphen supplies a hyphenation opportunity; it does not force the line breaking algorithm to use it. The algorithm can retain the unbroken word when its typesetting line width and paragraph cost permit that choice.