Soft hyphen

In computing and typesetting, a soft hyphen (ISO 8859: 0xAD, Unicode U+00AD SOFT HYPHEN, HTML: ­ ­) or syllable hyphen (EBCDIC: 0xCA), abbreviated SHY, is a code point reserved in some coded character sets for the purpose of breaking words across lines by inserting visible hyphens. Two alternative ways of using the soft-hyphen character for this purpose have emerged, depending on whether the encoded text will be broken into lines by its recipient, or has already been preformatted by its originator.

The use of SHY characters in text that will be broken into lines by the recipient is the application context considered by the post-1999 HTML and Unicode specifications, as well as some word-processing file formats. In this context, the soft hyphen may also be called a discretionary hyphen or optional hyphen. It serves as an invisible marker used to specify a place in text where a hyphenated break is allowed without forcing a line break in an inconvenient place if the text is re-flowed. It becomes visible only after word wrapping at the end of a line. The soft hyphen's Unicode semantics and HTML implementation are in many ways similar to Unicode's zero-width space.

To show the effect of a soft hyphen in HTML, the following words have been separated with soft hyphens:

Margaret­Are­You­Grieving­Over­Goldengrove­Unleaving­Leaves­Like­The­Things­Of­Man­You­With­Your­Fresh­Thoughts­Care­For­Can­You­Ah­As­The­Heart­Grows­Older­It­Will­Come­To­Such­Sights­Colder­By­And­By­Nor­Spare­A­Sigh­Though­Worlds­Of­Wanwood­Leafmeal­Lie­And­Yet­You­Will­Weep­And­Know­Why­Now­No­Matter­Child­The­Name­Sorrows­Springs­Are­The­Same­Nor­Mouth­Had­No­Nor­Mind­Expressed­What­Heart­Heard­Of­Ghost­Guessed­It­Is­The­Blight­Man­Was­Born­For­It­Is­Margaret­You­Mourn­For

On HTML browsers supporting soft hyphens, resizing the window will re-break the above text only at word boundaries, and insert a hyphen at the end of each line.

HTML4 describes it as a "hyphenation hint", though it suggests that that interpretation is not universal:

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