Edit in JSFiddle

<html>
    <head><title>mark tag in html5</title>
    </head>
    <body>
        <b>Below is the text with wbr tag, which tells browser to apply line break</b>      <p>aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa<wbr>aaaa</wbr>aaaaaaaaaaaaaaaaaaaaa</p><br />
        <b>Below text does not wrap. This text causes scroll-bar to appear.</b>      <p>aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa</p>
    </body>
</html>