what is the function of:
<script>
<A>
HREF
Definition List
<comment>
Just as it appears here, nothing. <script> is the start tag calling for a script of a type that hasn’t been identified, for example <script type="text/javascript">, <a href is the beginning of the start tag for a link, and <comment> is a comment you can place in your code for various reasons/purposes but isn’t formed correctly. A comment would be <!– Comment goes here –>.
Here is an explanation of definition lists
http://www.benmeadowcroft.com/webdev/articles/definition-lists.shtml