The Word Break Opportunity (wbr) element represents a position within text where the browser may optionally break a line, though its line-breaking rules would not otherwise create a break at that location.
This example uses the WBR element to create line breaks. In contrast, the NOBR element does not break lines.
<NOBR>This line of text will not break, no matter how narrow the window gets.</NOBR> <NOBR>This one, however,<WBR> will break after the word "however," if the window gets small enough.</NOBR>
A soft line break is a point inside a NOBR section at which a line break is permitted but not required.
On UTF-8 encoded pages, behaves like the U+200B ZERO-WIDTH SPACE code point. In particular, it behaves like a Unicode bidi BN code point, meaning it has no effect on bidi-ordering:
displays, when not broken on two lines, 123,456 and not 456,123.
For the same reason, the <wbr> element does not introduce a hyphen at the line break point. To make a hyphen appear only at the end of a line, use the soft hyphen character entity (­) instead.
Mozilla Developer Network : Article
Microsoft Developer Network: [Windows Internet Explorer API reference Article]