The definition of a soft hyphen (SHY) varies, depending on whether it is used in hyper text markup language (HTML) for computing or in printing. In HTML, the SHY is used to indicate where a line break should be. If it is typed at the end of a line, it will appear as a regular hyphen; if it is in the middle of a line, it will not show up as a visible mark. In desktop publishing, the SHY appears within a set hyphenation zone near the end of a line of text in order to break a word across two lines. For both HTML and desktop publishing a regular hyphen always appears as a regular character.
Not all internet browsers have always recognized the soft hyphen. In pages of browsers that ignore the code, it will always appear as a regular hyphen. It will also ignore HTML instructions for line breaks.
The soft hyphen is used by some spam email senders in an attempt to conceal message headers or body from spam filters. It can also be used to conceal a true URL so that a user will click on a link to a spam web page. While this method does fool some spam filters, there are other filters that have advanced features which are able to catch the trick.
For desktop publishing tasks such as layout and word processing, the soft hyphen follows most of the same rules as with HTML. One major difference is that the soft hyphen will disappear if text alterations due to changes in elements such as margins or pagination change the location of the hyphenation zone. The guidelines for where the hyphenation zone begins will typically be programmed into the software. Some programs allow for the parameters of this zone to be changed by the user.
Zero-width space (ZWSP) and non-breaking space work in a manner similar to the soft hyphen to change the way text appears. As with the soft hyphen, the zero-width space does not appear on the page. It is an invisible character used to indicate where a word breaks, or potentially where there should be a line break, when specific spacing instructions are needed. The non-breaking space, also known as a no-break space (NBSP), does the opposite of the soft hyphen and prevents a line break in a particular location. It also has an HTML code that is invisible on the published page.