<wbr> (Word Break)
This nonstandard element is used to indicate a place where a line break can occur if necessary. This element is used in conjunction with the <nobr> element, which is used to keep text from wrapping. When used this way, <wbr> can be thought of as a soft line break in comparison to the <br> element. This element is common to both Netscape and Microsoft implementations, though it is not part of any HTML standard.
id="unique alphanumeric value">
<nobr>A line break can occur here<wbr>but not elsewhere, even if the line is really long.</nobr>
Internet Explorer 2, 3, 4, 5, 5.5, 6
Netscape 1.1, 2, 3, 4, 4.5-4.8
Older versions of Internet Explorer documentation defined class, language, style, and title for this tag. However, they have little meaning, given this tag's purpose, and have since been eliminated from the documentation, though they may effectively be recognized in some manner by the browser parser.
Though this is an empty element and should be written as <wbr /> under XHTML, it does not need to be. It is not standard and will not validate anyway.
Standards-based browsers, such as Mozilla and Opera, do not support this tag but oddly seem to support <nobr>.