Zero-width space

The zero-width space (ZWSP) is a non-printing character used in computerized typesetting to indicate where the word boundaries are, without actually displaying a visible space in the rendered text. This enables text-processing systems for scripts that do not use explicit spacing to recognize where word boundaries are for the purpose of handling line breaks appropriately. Zero-width space is unicode character, and is located in the unicode General Punctuation block, and can be represented by HTML entities  or.

Purpose
The zero-width space marks a potential line break without hyphenation. Its semantics and HTML implementation are similar to the soft hyphen, but soft hyphens display a hyphen character at the point where the line is broken.

The zero-width space can be used to mark word breaks in languages without visible space between words, such as Thai, Myanmar, Khmer, and Japanese.

Unlike fixed-width spaces, in justified text that increases spacing between letters, characters adjacent to the zero-width space are spaced as if it was not present.

Example
To show the effect of the zero-width space in text, 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 have not been separated with these spaces: LoremIpsumDolorSitAmetConsecteturAdipiscingElitSedDoEiusmodTemporIncididuntUtLaboreEtDoloreMagnaAliquaUtEnimAdMinimVeniamQuisNostrudExercitationUllamcoLaborisNisiUtAliquipExEaCommodoConsequatDuisAuteIrureDolorInReprehenderitInVoluptateVelitEsseCillumDoloreEuFugiatNullaPariaturExcepteurSintOccaecatCupidatatNonProidentSuntInCulpaQuiOfficiaDeseruntMollitAnimIdEstLaborum

The first text only breaks at word boundaries, while the second text will not be broken at all. Resizing the browser window will re-break the text accordingly.

HTML
In HTML pages, the HTML element  functions as a zero-width space. In Internet Explorer 6, the zero-width space was not supported in some fonts.

Prohibition in domain names
ICANN rules prohibit domain names from containing non-displayed characters, including the 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, and input in HTML as , or. Contrary to what their names suggest, the character entities,  ,  , and   also refer to the zero-width space.

The TeX representation is ; the LaTeX representation is ; and the groff representation is.