Zero-width space


The zero-width space, abbreviated ZWSP, is a non-printing character used in computerized typesetting to indicate word boundaries to text processing systems when using scripts that do not use explicit spacing, or after characters that are not followed by a visible space but after which there may nevertheless be a line break. It is also used with languages without visible space between words, for example Japanese. Normally, it is not a visible separation, but it may expand in passages that are fully justified.

Usage

In HTML pages, the zero-width space can be used as a potential line-break in long words as an alternative to the <wbr> element. However, the zero-width space is not supported in some web browsers such as old versions of Internet Explorer.
To show the effect of the zero-width space, the following words have been separated with zero-width spaces:

Lorem​Ipsum​Dolor​Sit​Amet​Consectetur​Adipiscing​Elit​Sed​Do​Eiusmod​Tempor​Incididunt​Ut​Labore​Et​Dolore​Magna​Aliqua​Ut​Enim​Ad​Minim​Veniam​Quis​Nostrud​Exercitation​Ullamco​Laboris​Nisi​Ut​Aliquip​Ex​Ea​Commodo​Consequat​Duis​Aute​Irure​Dolor​In​Reprehenderit​In​Voluptate​Velit​Esse​Cillum​Dolore​Eu​Fugiat​Nulla​Pariatur​Excepteur​Sint​Occaecat​Cupidatat​Non​Proident​Sunt​In​Culpa​Qui​Officia​Deserunt​Mollit​Anim​Id​Est​Laborum

And the following words are not separated with these spaces:

LoremIpsumDolorSitAmetConsecteturAdipiscingElitSedDoEiusmodTemporIncididuntUtLaboreEtDoloreMagnaAliquaUtEnimAdMinimVeniamQuisNostrudExercitationUllamcoLaborisNisiUtAliquipExEaCommodoConsequatDuisAuteIrureDolorInReprehenderitInVoluptateVelitEsseCillumDoloreEuFugiatNullaPariaturExcepteurSintOccaecatCupidatatNonProidentSuntInCulpaQuiOfficiaDeseruntMollitAnimIdEstLaborum

On browsers supporting zero-width spaces, resizing the window will re-break the first text only at word boundaries, while the second text will not be broken at all.

Prohibited in URLs

rules prohibit domain names from including non-displayed characters such as zero-width space, and most browsers prohibit their use within domain names, because they can be used to create a homograph attack, where a malicious URL is visually indistinguishable from a legitimate one.

Encoding

The zero-width space character is encoded in Unicode as ​ .
The TeX representation is \hskip0pt; the LaTeX representation is \hspace; and the groff representation is \:.
Its semantics and HTML implementation are similar to the soft hyphen.

Citations