How do waiting lists work?

<p>I was wondering how waiting lists work and whether second semester senior grades have any bearing on acceptance.</p>

<p><a href="http://www.collegeboard.com/article/0,3868,5-28-0-124,00.html%5B/url%5D"&gt;http://www.collegeboard.com/article/0,3868,5-28-0-124,00.html&lt;/a&gt;&lt;/p>