 <p>It removes all the whitespace (replaces all whitespace matches with empty strings). </p> <p>A wonderful regex tutorial is available at <a href="http://www.regular-expressions.info/">regular-expressions.info</a>. A citation <a href="http://www.regular-expressions.info/unicode.html">from this site</a>: </p> <blockquote> <p>\p{Z} or \p{Separator}: any kind of whitespace or invisible separator. </p> </blockquote>